Final answer:
The correct phrase to complete the given sentence is "As for Howard, I do not care what happens to him." The phrase "As for" is used to shift focus to a different subject, which in this case is Howard.
Step-by-step explanation:
The sentence provided by the student uses a context that implies a shift of focus from one subject to another, specifically from the student's decision to leave the city to their opinion about a person named Howard. The correct phrase to complete the sentence and create this shift in focus would be "As for Howard, I do not care what happens to him."
"As for" is often used to introduce a subject or topic that is different from the one being discussed. It is a way of addressing a specific point or person after talking about a general or different subject. Therefore, option 'a' is the correct answer.
The other options do not fit as well in this context: "What about" is usually used to bring up a new subject for consideration or to ask for information about it; "Talking of" is informal and typically used when the speaker’s comment is directly related to the subject at hand; "As far as" is used to discuss the extent of something and doesn't match the sentiment of the sentence.