instruction:
Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
question:
Gabbro is a dark dense rock that can be found in the oceanic crust.
answer:
Gabbro is a dark dense rock that can be found in what?

question:
Induced or spontaneous are the two methods in which mutations arise in dna.
answer:
What are the two methods in which mutations arise in dna?

question:
The values of independent variables are controlled by the experimenter over the course of an experiment.
answer:
The values of which factors are controlled by the experimenter over the course of an experiment?