Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Gabbro is a dark dense rock that can be found in the oceanic crust.
Gabbro is a dark dense rock that can be found in what?

The height of the wave is used to determine the magnitude of an earthquake.
What measurement of the wave is used to determine the magnitude of an earthquake?

Antismoking groups have proposed that cigarette advertising in all media be banned entirely.

Who has proposed that cigarette advertising in all media be banned entirely?