Assertion: Blood in cockroach is colourless haemolymph with no respiratory pigment.

Reason: Respiration in cockroach occurs through diffusion in haemolymph.

• If both assertion and reason are true and reason is the correct explanation of assertion. 

• If both assertion and reason are true but reason is not the correct explanation of assertion. 

• If assertion is true but reason is false. 

• If both assertion and reason are false.

C.

If assertion is true but reason is false. 

The colourless blood or haemolymph of cockroach has a clear plasma and numerous white corpuscles called haemocytes. Being devoid of any respiratory pigment, it does not serve for gaseous exchange. Its plasma contains about 70% water. Rest of it is composed of amino acids, uric acid, proteins, sugars, fats, and salts of sodium, potassium, calcium and magnesium. Transportation of these materials between different parts of body is the main function of haemolymph.
In all terrestrial insects, like cockroach, every tissue of body is in direct contact with atmospheric air for gaseous exchange. A complicated system of numerous shiny, transparent and branched air tubes or tracheae is found for this purpose in the haemocoel cavity. Atmospheric air enters into and escapes out from this system through ten pairs of slit-like apertures called stigmata or spiracles, located on lateral sides of body