Which of the following statements about immune response are correct?
P. T cells are activated by antigen-presenting cells.
Q. Foreign peptides are not presented to helper T cells by class II MHC proteins.
R. Dendritic cells are referred to as professional antigenpresenting cells.

A. P and R only

B. P and Q only

C. Q and R only

D. P, Q and R

Answer: Option A