In which examples does a vitamin or mineral function as a cofactor?
A. Hydroxylase enzymes require vitamin C during collagen synthesis.
B. Calcitriol, a form of vitamin D, regulates calcium levels in blood.
C. Ribosomes require phenylalanine to construct proteins.
D. DNA polymerase requires zinc to replicate DNA.

A -Hydroxylase enzymes require vitamin C during collagen synthesis.

Explanation:

Vitamin C is essential for synthesis of collagen. Vitamin C is the essential cofactor for the two enzymes required for collagen synthesis which are  prolyl hydroxylase (to stabilize the collagen molecule) and lysyl hydroxylase (to give structural strength cross-linking).

In addition to its antioxidant functions, vitamin C regulates the synthesis of the structural protein collagen. The role of vitamin C in the hydroxylation of collagen molecules is well characterized. Hydroxylation of collagen is necessary for its extracellular stability and support of the epidermis.

relative humidity, temperature and dew point -- are bound together in the mathematical relationship below. relative humidity changes when temperatures change. because warm air can hold more water vapor than cool air, relative humidity falls when the temperature rises if no moisture is added to the air. so i would say a

atp is used for energy.