The effects of a deficiency of vitamin d are most readily observed in the

Solution:

In children, it is easily found it can cause rickets. Rickets is a rare disease that causes the bones to become soft and bend.  In adults, severe vitamin D deficiency leads to osteomalacia. Osteomalacia causes weak bones, bone pain, and muscle weakness.

It happens due to the lack of Calcium.

oxygen +1 most likely

the answer is c. it will give up it's valence electron to the other atom.