Which of the Following Statements Is NOT a Reason Why

Multiple Choice

Which of the following statements is NOT a reason why humans are the most difficult organism to study?

A) For ethical reasons, an ideal experimental design may not be allowed to be performed with human subjects.
B) Some types of double-blind experiments cannot be performed with human subjects.
C) Long-term (longitudinal) studies may involve inaccurate reporting by the participants.
D) Longitudinal studies of human subjects can be very expensive.