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

Amount of salt are aquatic biomes often classified.
How are aquatic biomes often classified?

When the smooth muscle relaxes, the arterioles dilate, allowing blood to enter the capillaries.
When the smooth muscle relaxes, the arterioles dilate, allowing blood to enter the what?

The core is the sun's innermost layer.

What is the suns innermost layer called?