Normal sexual behavior is that which
a. reflects the average or median behavior of a group
b. is supported by religious teachings
c. reflects the preferences of those of high status in a society
d. leads to successful reproduction

a. Represents the average or median behaviour of a group.

Explanation:

Any 'normal' behaviour denotes the usual aspects of the variable/ attribute, as represented by average for a group of people.

Examples : Normal Heart Beat - 70 to 80  is a range decided around average after examining various people's heart beat.

Similarly, Normal Sexual Behaviour is average behaviour attributed after evaluating sexual behaviour of various people.

- "ethical issues. deception – the participants actually believed they were shocking a real person and were unaware the learner was a confederate of milgram's. however, milgram argued that “illusion is used when necessary in order to set the stage for the revelation of certain difficult-to-get-at-truths.” "

- "milgram's work was conducted in the early 1960s before the current.the studies ignited a debate about the ethical treatment of participants. what appear to be dangerous, if not deadly, electric shocks and the by today's ethical standards, many questions about the research have gone unanswered."

depends on what they need