Specificity Is an Important Characteristic of Intercellular Communication; Which of These

Specificity is an important characteristic of intercellular communication; which of these best explains why it occurs?

A) because all cells have very similar compositions of their phospholipid membranes
B) because protein receptors are only located on the surface of target cells
C) because all cells have the same DNA,so any cell can express protein receptors for a specific chemical
D) because chemical messengers are all proteins
E) because protein receptors for chemical messengers are only expressed in specific target cells