Out of the 200 million ejaculated sperm, only about _________ reach the vicinity of the egg.

A. The small intestine absorbs lipids but does not produce HDL (high-density lipoprotein).

B. The pancreas produces enzymes and hormones, but it does not produce HDL.

C. The liver is the primary organ responsible for the synthesis of HDL. HDL is involved in reverse cholesterol transport, carrying cholesterol from tissues back to the liver.

D. The gallbladder stores and concentrates bile but does not produce HDL.

A. The bicarbonate, phosphate, and protein: The major chemical buffer systems in the body are the bicarbonate buffer system, the phosphate buffer system, and the protein buffer system. These buffers help maintain pH balance in the blood and other fluids.

B. The urinary and digestive: The urinary and digestive systems are involved in excretion and digestion, not buffering.

C. The bicarbonate, nucleic acids, and protein: Nucleic acids are not major buffering systems in the body; the bicarbonate, phosphate, and protein systems are the primary ones.

D. The urinary and respiratory systems play roles in regulating acid-base balance through excretion and gas exchange but are not chemical buffer systems themselves.