． "Herding effect" - In a flock of sheep rushing left and right, once the leader who attracts attention appears, other sheep will imitate and rush forward without thinking, regardless of whether there are traps in front or on the other side. There will be better grass. Whoever can be at the forefront will be able to take the initiative earlier and faster. The "herding effect" reflects (　)

A. The main contradiction plays a decisive role in the development of things

B. Secondary contradictions do not play a decisive role in the development of things

C. The main aspects of contradiction determine the nature of things

D. The secondary aspects of the contradiction have no effect on the nature of the thing

Analysis: Choose A. The "herding effect" reflects the important guiding role of the leader in the flock, which means that the main contradiction plays a decisive role in the development of things, so the answer is A. Item C does not meet the purpose of the question, and both opinions B and D are wrong and should be eliminated.