The secondary or memory response:
a. occurs after the primary response has activated null cells.
b. provides better protection than the primary response.
c. is less effective in antibody production.
d. produces different antibodies than those produced in the primary immune response.
e. does not protect the body after the first exposure.

b. provides better protection than the primary response.

Explanation:

An immune response occurs when an individual responds to the presence of a foreign invader. These invaders can be viruses, bacteria, fungi etc.

The secondary immune response is activated when a person is exposed to an antigen a second, third or fourth time. The cells involved in this immune response are the B lymphocyte cells.

B

Explanation:

The primary B-cells usually provide protection by plasma cells formation. However because few B-cells are sepcific to the antigens, they are slow in the protection.After some divided to form plasma cells, the rest formed the memory cells.

These are B-cells or secondary cells, remain in the circulating blood with specific receptors to the  preceding antigen(memory)  attacked by the primary B-cells. Therefore if  the same antigen enters the body again,they  are quickly recognized by these memory cells, thus they divided quickly,and attack the antigens.Thus they provided better and faster  protection than the primary-B cells.