When doing medical research with human subjects, which four limitations are unavoidable? A. It’s often impossible to repeat trials on the same subjects.

B. Subjects may report an inaccurate medical history.

C. It can be difficult to control all possible variables.

D. It’s impossible to come up with testable scientific questions for human subjects.

E. There are ethical or privacy concerns to consider.

Will give brainliest pls help ( I don't know whether B or D are the incorrect answers).