Final answer:
Twelve students answered Mr. Chiu's question.
Step-by-step explanation:
From the given options, we can determine the number of students who studied for different hours as follows:
A. Eleven students answered Mr. Chiu's question.
B. Twelve students answered Mr. Chiu's question.
C. Three people studied for two hours.
D. Four people studied for three hours.
Therefore, the correct answer is B. Twelve students answered Mr. Chiu's question.