Cholesterol is a. not essential in the diet; the human body can synthesize it b. all of these choices are correct c. not found in foods of plant origin d. an important part of human cell membranes and is necessary to make some hormones

b. all of these choices are correct

Explanation:

Cholesterol is the steroid alcohol and type of lipid. Steroid alcohol or sterols are a type of steroid and steroids are type of lipids. It is essential for human life.

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.