True about serology of rickets is –: (A) a, (B) b, (C) c, (D) d
Answer is C. Rickets is a metabolic disorder of growing bone (immature skeleton) primarily caused by lack of -

i)    Vitamin D or                  ii) Calcium or                       iii)          Phosphate

The end result is defective mineralization of bone.
Depending on the cause - Rickets is classified into following types -

Clinical variants of Rickets