Answer:
The best option for the meaning of "demonstrate" in paragraph 4 is D. protest.
Step-by-step explanation:
If we look up the meaning for the verb "to demonstrate", we will find the following:
1. to show clearly that something exists or that it is true;
2. to do something yourself in order to show someone how to do it;
3. to protest about/against something in a public place with other people.
From the meanings listed above, we may conclude that "demonstrate" can signify "display", "explain", or "protest". The first option given in the question - "conceal" - is already eliminated. However, to choose the best option we must take the context of the excerpt into consideration.
When the author says, "organized many events to demonstrate against the segregation between whites and blacks", "demonstrate" can be successfully replaced by "protest" without any loss in its meaning. It was clearly a public gathering with the aim of fighting against segregation. In conclusion, the verb "demonstrate" is employed with the meaning of D. protest in paragraph 4.