Answer:
the correct answer is see.
Explanation:
it is wat it isssssssssss
The answer to this question would be: vitamin D
The UV is needed by the skin to make previtamin D3. Previtamin D3 or cholecalciferol made from the skin will be changed in the liver into 25- hydroxyvitamin D3 and then sent to the kidney to be changed into 1,25- dihydroxyvitamin D3. The last change in the kidney will active the vitamin D. Vitamin D has a role in the calcium absorption which was will strengthen the bone tissue.
I think it's a solar power might seem strange or futuristic but it's already quite common place you might have a solar powered quartz watch on your wrist or solar powered pocket calculator
Answer:
frictonal force due to the surface of irregularities
