Use reasoning to lead to the answer of the following question:
He felt stuffy in the shirt, he began to unfasten the what style of shirt?\nOptions:\n- pull up\n- zip up\n- tie up\n- do up\n- button up
 Reasoning process:
User
He felt stuffy in the shirt so he began to unfasten and button up the shirt. Therefore, the final answer is button up.
Assistant