Question

When an explanation to a problem is accepted as always true, it is
a. law theory hypothesis fact?

Answer 1

I believe the best answer is law, as scientific laws are accepted to be true under the proper conditions. 

Answer 2

Answer: law

Explanation: A law is a rule that is used to explain the observation of a body. It could be represented in form of verbal or mathematically.

when the answer is considered as always true under every condition tested, it becomes a law that would be used to know other variables.