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

Example Input: What structure consists of an outer layer of cells called the trophoblast and an inner cell mass called the embryoblast?
Example Output: blastocyst

Example Input: In the past, what colliding with planet earth has caused many organisms to die off?
Example Output: asteroids

Example Input: A measure of the disorder of a system is called its what?
Example Output:
entropy