1.
a)
Answer:
A direct address is a rhetorical tool employed whenever the speaker directly addresses his or her listeners, using the 1st- and 2nd-person voice (I/we and you) instead of the impersonal 3rd-person voice (he/she/they).
Explanation:
Instead of a detached, objective stance employed in this part of the sentence, I would fare better if I spoke to you directly. We are in the same boat, and if we don't help each other, nobody else will! Why would you just sit and listen what somebody else is telling you? Listen to your own instincts! Act on them!
The above (made-up) example clearly shows what a direct address is. Beside using the I/we and you as personal pronouns, it also makes use of imperatives - verbs that are meant as commands or instructions to others ("listen", "act"). Such forms always manage to grab the listener's attention - think, for example, of modern blog posts that often speak directly to "you", the reader.
b)
Answer:
Dr. King directly addresses his "Fellow Clergymen" thereby positioning himself as one of them - and asserting that they should also be able to put themselves in his shoes.
Explanation:
One of his main points is that the injustice done to one person necessarily affects each and every person everywhere. This "inescapable network of mutuality" is embodied in his frequent use of the collective pronoun "we". It means that "our" predicament is one and the same.
On the other hand, he often juxtaposes the personal pronoun "you" to the "we", for example: "You deplore the demonstrations taking place in Birmingham." As if to say: "we" personifies all of our similarities, whereas "you" is the embodiment of our differences (which, again, only "we" can transcend together). When anyone's basic human rights are endangered, everyone's rights are at stake. And it's this collectivity that he's aiming at.
c)
Answer:
By using direct address, King appeals to his addressees' empathy. By pointing out their mutual similarities and differences, he is trying to enhance the emotional effect of his arguments.
Explanation:
The point of his letter is the necessity of action. The direct address sets this point in motion as the addressee can't just think "this doesn't concern me" and stop reading. To use King's own words, the direct address "seeks so to dramatize the issue that it can no longer be ignored". It raises the tone, engages the listener/reader, drawing them into the subject head-on, leaving no room for indifference or apathy.
2.
Answer:
I would say the most effective allusion is the one referring to Jesus and the Calvary, in the paragraph where he talks about extremism that he'd been accused of.
"In that dramatic scene on Calvary's hill three men were crucified. We must never forget that all three were crucified for the same crime--the crime of extremism. (...) The other, Jesus Christ, was an extremist for love, truth and goodness, and thereby rose above his environment."
Explanation:
When someone addresses a group of ministers, no allusion can be more powerful and effective than an allusion to Christ himself. As a minister, King is well aware of that. The two men, Christ and King, were both controversial figures that fought for peace, love, and tolerance, but were nevertheless labeled as extremists who brought dissent among their contemporaries and disrupted the respective social-political systems they lived in. King is trying to legitimize his actions by putting them alongside Christ's own course of action. As if to say: this is what Christ would do!
3.
Answer:
I would say King's main goal is to provoke his audience into action. At that point, while sitting in jail and watching the injustice that is still going on outside, he is beyond mere attempts to inspire, much less to calm his followers and/or adversaries. His main idea is the necessity of civil action, and action needs to be triggered and provoked, rather than just contemplated upon. These provocations include critique of his opponents' words and actions (including the lack thereof).
Explanation:
Example: "It is unfortunate that demonstrations are taking place in Birmingham, but it is even more unfortunate that the city's white power structure left the Negro community with no alternative."
The "white power structure" is comprised, among others, of the very people to whom King is addressing his letter - white clergymen who should know better than to undermine their fellow brothers' and sisters' just cause. In this sentence, he is trying to underline their hypocrisy that had compelled them to stay silent at the racial injustice while voicing their anger against the demonstrations. It's a clear provocation. A few paragraphs later, he proceeds in the same critical tone: "Isn't this like condemning a robbed man because his possession of money precipitated the evil act of robbery?"