Please complete the following sentence.

Membrane rafts are

a. depleted in cholesterol, sphingolipids, and GPI-linked proteins. The bilayer is thicker in the raft domains than in the surrounding membrane.

b. depleted in cholesterol, sphingolipids, and GPI-linked proteins. The bilayer is thinner in the raft domains than in the surrounding membrane.

c. rich in cholesterol, sphingolipids, and GPI-linked proteins. The bilayer is thicker in the raft domains than in the surrounding membrane.

d. rich in cholesterol, sphingolipids, and GPI-linked proteins. The bilayer is thinner in the raft domains than in the surrounding membrane.