Shivering occurs when many muscles contract a little bit all at once.
Almost all birds use shivering as a short term adjustment to the cold.
Many muscles contract a little bit all at once as a short term adjustment to the cold.
What can contract a little bit all at once as a short term adjustment to the cold?
Options:
a) that metal
b) muscles
c) Weight
d) stomach
e) mammals
f) atoms
g) ligaments
h) sweating