When doing medical research with human which four limitation are unavoidable

1- It's often impossible to repeat trials on the same subjects. 2-Subjects may report an inaccurate medical history. 3-It can be difficult to control all possible variables. 4-It's impossible to come up with testable scientific questions for human subjects.

Explanation:

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Explanation:

I cant help you ask someone else I have not covered that in my biology course