Respiration in insects Is called direct because

Options

A. The tissues exchange `O_(2)//CO_(2)` directly with the air in the tubes
B. The tissues exchange `O_(2)//CO_(2)` directly with coelomic fluid
C. The tissues exchange `O_(2)//CO_(2)` directly with the air outside through body surface
D. Tracheal tubes exchange `O_(2)//CO_(2)` directly with the haemocoel which then exchange with tissues

Answer

d