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

Soft of these best describes the way a feather feels.
Which of these BEST describes the way a feather feels?

Deep currents are caused by differences in density at the top and bottom of the ocean.
What is caused by differences in density at the top and bottom of the ocean?

Visible light do jellyfish use to startle predators.

What do jellyfish use to startle predators?