Answer: D, people are unable to resist the desire to follow the crowd because it is part of human psychology
Explanation: I believe this is the correct answer not only by using process of elimination but by logical sense. Automatically, choices b and c cancel out because they are not main or central ideas, just examples or statements made in the passage. So we’re left with a and d. When you think about it, d makes more sense than a because a talks about experiments. Sure, the whole passage has to do with experiments, but it is not the message trying to be said. D would therefore be the correct answer.