Laud Humphreys Wrote His Dissertation on Anonymous Homosexual Encounters in the Men's

Laud Humphreys wrote his dissertation on anonymous homosexual encounters in the men's rooms of public parks. To gather data, he acted as a lookout for his participants, but he also secretly noted license-plate numbers as the men left so he could get their names and addresses. He picked about fifty of the men the next year and, claiming to be performing a health survey, interviewed them in their homes. His descriptions of the interviews made it possible for many of the men (and their families) to recognize themselves when the dissertation was published. Why do many sociologists consider this research method to be unethical?

A) It used terminology that was confusing to the interview participants.
B) It put Humphreys at risk for arrest or retaliation.
C) It harmed the reputation of the city where Humphrey's participants lived.
D) It failed to protect the biographical anonymity of Humphrey's participants.