Together with the skin and the liver, the kidney synthesize the active form of vitamin d. a)calcitoninb)calcitriolc)erythropo ietind)renine)angiotensin

B)calcitriol

Explanation:

The active form of vitamin D is calcitriol (1,25-dihydroxy-vitamin D) which is synthesized by the kidney.

Other organs which play a role in the synthesis of Vitamin D are skin and liver.

In the presence of sunlight, a compound 7-dehydrocholesterol is converted into Vitamin D. Vitamin D is converted into 25-hydroxy-vitamin D (calcidiol) in the liver which is further converted into 1,25-dihydroxy-vitamin D (calcitriol) in the kidney which is the active form of vitamin D.

Referring to other options,

A)calcitonin

It a hormone released by thyroid gland and is responsible for calcium and phosphate levels regulation. Therefore, it is an incorrect answer choice.

B)calcitriol

This is the correct answer choice.

C)erythropoietin

This is a hormone released by kidney and is responsible for increasing red blood cell production. Therefore, it is an incorrect answer choice.

D)renin

This is a hormone released by the kidney and is responsible for blood pressure regulation. Therefore, it is an incorrect answer choice.

E)angiotensin

This is a peptide hormone responsible for blood pressure regulation.

Therefore, it is an incorrect answer choice.