Professional psychological associations require researchers to minimize infection, illness, and pain in animal subjects.

A. obtain informed consent before using any animals as subjects in research.

B. test only dependent, not independent, variables on animals.

C. study animals only in their natural environment.

D. protect only cats, dogs, and primates, not mice or rats, from unnecessary pain.

The correct answer D.

Explanation:

The professional psychological association established some ethical regulation known as The APA ethics code that is an essential ethic code for psychological researchers to work.

It has many standards related to the clinical practice of psychology but main concerned ethical standard are taking consent, no use of non-primates and cat or dogs as animal subject and other like debriefing, deception and many other. It allows subjects like rats or mice for clinical purposes.

Thus, the correct answer is an option - D.