What is the difference between PIM sparse mode and PIM dense mode?

What is the difference between PIM sparse mode and PIM dense mode?
A . Sparse mode supports only one switch. Dense mode supports multiswitch networks.
B . Sparse mode floods. Dense mode uses distribution trees.
C . Sparse mode uses distribution trees. Dense mode floods.
D . Sparse mode supports multiswitch networks. Dense mode supports only one switch.

Answer: C