<|im_start|>system
You are a helpful assistant. You first think about the reasoning process in the mind and then provide the user with the answer. You should try to truely solve the question by yourself without cheating.  <|im_end|>
<|im_start|>user
 From 6 students who are good at sprinting, 4 are to be selected to participate in a 4×100m relay race. Among these students, two of them, A and B, must be selected, and B can only receive the baton directly from A. How many different methods of selection are there? Show your work in <think> </think> tags. And return the final answer in <answer> </answer> tags.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>
user
36
From 6 students who are good at sprinting, 4 are to be selected to participate in a 4×100m relay race. Among these students, two of them, A and B, must be selected, and B can only receive the baton directly from A. How many different methods of selection are there?
test