Go through what is physically painted on a matchbox and what each option really is.
Option A, Chile saltpetre (sodium nitrate): this compound is mainly known as a nitrogen source for fertilisers and occasionally in explosive mixtures, it has no established role in matchstick or matchbox manufacture.
Option B, Indian saltpetre (potassium nitrate): this is the classic oxidiser used in old style gunpowder and fireworks, but it is not the ingredient used on the striking surface of a modern safety matchbox.
Option C, red phosphorus: this is applied, mixed with powdered glass and a binder, to the striking strip on the side of the matchbox. Friction from striking the match head converts a trace amount into white phosphorus, which flares up immediately and ignites the potassium chlorate and fuel mixture coated on the match head itself. Red phosphorus is preferred over the far more dangerous white phosphorus because it is much safer to store, being non toxic and not self igniting in ordinary conditions.
Option D, sodium bicarbonate: this common household chemical is a mild base used in baking and antacids, it has no oxidising or flammable property that would let it play any role in a matchstick.
Since red phosphorus is the real functional ingredient on the striking surface, option C is the correct answer.