The composition of which of the following is highest in the cell membrane?: (A) Proteins, (B) Phospholipids, (C) Cholesterol, (D) Carbohydrates
Answer is A. As per the 12th Edition of Guyton, the following are the approximate composition of a cell membrane/ plasma membrane.

Proteins- 55%
Phospholipids- 25%
Cholesterol-13%
Other lipids- 4%
Carbohydrates- 3%