$\mathrm{i}-\mathrm{c}, \mathrm{ii}-\mathrm{a}, \mathrm{iii}-\mathrm{b}, \mathrm{iv}-\mathrm{d}$.

i - c, ii - b, iii - d, iv -a.

$\mathrm{i}-\mathrm{c}, \mathrm{ii}-\mathrm{a}, \mathrm{iii}-\mathrm{d}, \mathrm{iv}-\mathrm{b}$.

i - c, ii - d, iii - a, iv - b.

F-cells (pp cells)

Delta cells ( $\delta$ cells)

Beta cells ( $\beta$ cells)

Alpha cells ( $\alpha$ cells)

i - b, ii - c, iii - d, iv -a.

i - b, ii - c, iii - a, iv - d.

i -d , ii -b , iii -a, iv -c .

i -d, ii -c, iii -c, iv -a .

Thyroid gland

Pineal gland

Pituitary gland

Parathyroid gland