Malpighian tubules are
a)	Excretory organs of insects	b)	Excretory organs of frog
c)	Respiratory organs of insects	d)	Endocrine glands of insects

(a)

Malpighian tubule are the excretory organs of insects. These open at the junction of midgut and hindgut (ileum) in cockroach. Malpighian tubules absorb excretory substances from haemolyph and fat bodies and pass into the proctodaeum. The excretory product of insects is uric acid related with water conservation in the body. These tubules are related with homeostasis, Osmoregulation and excretion.