It can be inferred from the passage that one reaso...

Câu hỏi: It can be inferred from the passage that one reason that sociologists may become frustrated with questionnaires is that _________.

A. respondents often do not complete and return questionnaires

B. questionnaires are expensive and difficult to distribute

C. respondents are too eager to supplement questions with their own opinions

D. questionnaires are often difficult to read