Given a scientific question, generate a correct answer to it.

Ex Input:
In vertebrates, a system of what structures attached to the endoskeleton enables movement?

Ex Output:
muscles

Ex Input:
What are the two types of vascular tissues found in vascular plants?

Ex Output:
xylem and phloem

Ex Input:
What waves are the broad range of electromagnetic waves with the longest wavelengths and lowest frequencies?

Ex Output:
radio