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

Solid is characterized by molecules with minimal movement and strong forces between them.
Which state of matter is characterized by molecules with minimal movement and strong forces between them?

All enzymes have an optimal temperature and ph.
All enzymes have an optimal temperature and what?

Toxins is contained in the skin of brightly colored poison dart frogs.

What is contained in the skin of brightly colored poison dart frogs?