I believe the correct answer is theory
The penis is the male copulatory organ, so penis is the answer
(1) medicine amount: the error in conversion of US to the metric system may hinder the patient from getting the right dosage of medicine.
(2) experiment results: especially if the experiment is of something very relevant, the error will lead to very unfavorable experiences from all the parties
(3) simple assignment/test: will lead to failure if the units used during the exam are not consistent.
Because there has been no change in their environment, or/and no predators.
