human bone, muscle, and nerve ceils all contain the same number of chromosomes with the
same complement of genes. what enables these cells to perform specialized activities?

These cells are able to perform specialized activities due to the 'Gene Regulation' which controls the expression of various genes.

Explanation:

Gene regulation can be explained as a process by which the cells control the expression of each gene among various genes in the genome. Gene expression is the pattern that any gene exhibits to perform certain functions or activities. For example, brain cells control the expression of the gene that exhibits characteristics like thinking, reasoning, and calculating. Such expressions are suppressed in other cells like cells of the heart. Therefore, every cell of various part expresses their gene function, and thus, perform the specialized activity in the manner their gene cells are expressed.

answer: - b cells

explanation: -

so, the b cells mediate their action by identifying the antigens present on the surface of the pathogens and then producing antibodies in return to mediate its effect.