The deficiency of vitamin $C$ causes

Which of the following vitamins should be regularly supplied in the diet?

Fat soluble vitamins are $:$
$A.$ Vitamin $B_1$
$B.$ Vitamin $C$
$C.$ Vitamin $E$
$D.$ Vitamin $B_{12}$
$E.$ Vitamin $K$
Choose the correct answer from the options given below $:$

Deficiency of vitamin $B_1$ causes the disease

Which of the following vitamins has isoprene units in its structure?

Deficiency of which vitamin causes rickets?