What is the main function of spindle fibers?

a.) to condense chromatin into chromosomes.
b.) to replicate the chromosomes before cell division.
c.) to decondense chromosomes following mitosis.
d.) to separate chromosomes during mitosis.

The correct option is D. To separate chromosomes during mitosis.

Explanation:

All cells of the body replicate through the process of mitosis except the sex cells. The formation of the spindle fibres is a very important step in the mechanism of mitosis and meiosis both.

Spindle fibres are present on the opposite poles and pull the chromosomes to each side. As a result, the chromosomes get separated into two halves and gametes are formed. This process also ensures that equal division takes place.

regulation of gene expression. gene expression can be regulated by various cellular processes with the aim to control the amount and nature of the expressed genes. these regulatory proteins bind to dna and send signals that indirectly control the rate of gene expression

explanation:

white blood cells or wbc s are mainly 2 types-

1.agranulocytes

2.granulocytes

the monocytes or macrophages of agranulocytes , dendritic cells which are accessory leucocytes, and b cells which is one type of lymphocytes   identify the antigens present on the pathogen's surface. these three cells are called antigen presenting cells(apc) which are phagocytes and destroy the antigens by secreting antitoxins. besides this leukocyte is always plays vital role in the immunity of the body.