Which of the following has the thickest layer of muscle? A, Vein. b, capillary C, artery D, venule

c

Explanation:Blood vessels are the channels or conduits through which blood is distributed to body tissues. The vessels make up two closed systems of tubes that begin and end at the heart.

answer: the correct option is d. enzyme

lactase and carbonic anhydrase are the examples of enzymes.

lactase is an enzyme, which is present in the small intestine of mammals. it in the digestion of the disaccharide, lactose ( milk sugar) by converting it into two monosachharide, which are glucose and galactose.

carbonic anhydrase is present in the red blood cells. this enzyme plays significant role in the transport of co₂. it in the conversion of co₂ and h₂o into carbonic acid, which is then dissociated into bicarbonate ions and hydrogen ions.