All the following conditions must be present for a fire to start except

A. a heat source (such as a spark).

B. fuel (such as wood or gasoline).

C. oxygen to support the fire.

D. nitrogen to support the fire

The answer is the last one so D

The only things you need to start a fire is a heat source to get it started, fuel that the heat source can use to feed on and grow larger, and oxygen to support the flame.

So the answer is it needs everything except nitrogen to start the fire.

Fun fact - Nitrogen will inhibit the fire, as it's going to dilute the oxygen. More oxygen = better fire.