Mutations in the genes encoding for igm would
a. block macrophage stimulation by antigens.
b. block the synthesis of b cells during hematopoiesis.
c. prevent the onset of the primary immune response.

c. prevent the onset of the primary immune response.

Explanation:

In vertebrates , the IgM is produced by the body of vertebrates . It is mainly responsible for the primary immunity of the body , The mutations in the IgM gene leads to some alterations of the primary immunity .

But , the synthesis of B cells are controlled by bone marrow along with the IgH .

The B cells control the Macrophages stimulation of the antigens .

abducens nerve on the right

explanation:

because they were born with essential oils in their veins