The following non-metal form acidic oxides with oxygen except?

A.

phosphorus

B.

sulphur

C.

carbon

D.

chlorine

Correct answer is C

The oxides which neither react with acids nor react with bases are known as neutral oxides. 

Carbon monoxide neither reacts with acids nor reacts with bases.

Thus, carbon monoxide is a neutral oxide, produced when combustion reactions are not fully completed, either through lack of oxygen or due to low mixing