The correct answer is - has small crystals.
Basalt is an igneous rock, formed from the lava flows that cool off pretty quickly, either on the surface, or very close to the surface. The cooling appears to be very quick because the lava is exposed to a much lower temperature that its own temperature, thus starting to cool of, loses its liquidity/viscosity, and becomes solid. Since the cooling off appears to very quick, the basalt has very small crystals, often, even unnoticeable with bear eye, and this is because the rock forms very quickly and there isn't time for creating a more massive crystal structure as the extrusive igneous rocks.
