The primary immune response .

a. has a lag period while B cells proliferate and differentiate into plasma cells
b. occurs when memory cells are stimulated
c. occurs more rapidly and is stronger than the secondary response
d. is another name for immunological memory

a. has a lag period while B cells proliferate and differentiate into plasma cells

Explanation:

When the body comes in contact with foreign antigen for first time it is accompanied by primary immune responses, a lag period occurs in which no antibody is produced but activated B cells are transformed into plasma cells, this is called lag phase. The lag period may be as short as 2-3 days but is sometimes longer.

white blood cells consist of B cells which are formed in the bone marrow. Growing B cell (after first exposure) produces several copies of one type of antigens as a surface antigen receptor. The entire population of B cells has the ability to directly bind to millions of different antigens. If the antibody on a B cell's surface bind to an antigen, the cell will be primed to undergo proliferation and differentiation.

Hence, the correct option is a.

i'd say that the moon rock is about 2.2 billion years old.

as the gila monster consumes the eggs or young of the desert cottontail and gambel's quail, thus its main food supply is only accessible for a restricted time duration every year. however, for this, the gila monsters exhibit three adaptations, which elevate their survival rate in the desert condition.  

first, is that they possess huge bodies, and can consume greater concentrations of food during a small period. secondly, they require to feed infrequently as they can accumulate fat in their tails. ultimately, their rate of metabolism is very low, so that they can burn their reservoirs of fat gradually.