Which of the following statements is TRUE about professor Kimballs survey？A．Some people do

Which of the following statements is TRUE about professor Kimballs survey？

A．Some people don"t want to take it because it"s too time-consuming.

B．The results might not be objective enough.

C．The survey aims to measure Americans" happiness.

D．The survey has been conducted for three months.

请帮忙给出正确答案和分析，谢谢！