Comets are made mostly of ice and dust. As comets get close to the sun, they start to “melt” and release what?

Question

Accepted Answer

Steam, gas and dust. C is correct because comets release a mix of ice vapor (steam), gases from sublimation, and dust. A is incorrect because it misses the gaseous components released by volatile ices. B is incorrect because it omits the steam component which comes from melting water-ice or other volatile ices. D is incorrect because the comet does release material when approaching the sun.