According to the interviewee, which is the main difference between the first and the secon

According to the interviewee, which is the main difference between the first and the second poll？

A．The type of respondents who were invited.

B．The way in which the questions were designed.

C．The content area of the questions.

D．The number of poll questions.

请帮忙给出正确答案和分析，谢谢！