crystal size in igneous rocks is determined by?\na. the rate melted rock cools\nb. the type of magma…

Brief Explanations:

The rate at which melted rock (magma or lava) cools affects crystal size in igneous rocks. Slower - cooling allows more time for atoms to arrange into larger crystals, while rapid cooling results in smaller crystals or even glassy textures. Magma composition and type of magma emplacement have some influence on rock characteristics but are secondary to cooling rate in determining crystal size. Tectonic plate movement speed is not directly related to crystal size in igneous rocks.

Answer:

A. the rate melted rock cools