The faster an igneous rock cools, the its crystals will be.

-more colorful
-more irregular
-larger
-smaller

The correct answer is - smaller.

The size of the crystals of the igneous rocks is directly affected by the speed of the cooling of the magma.

If the magma cools off very quickly, than the size of the crystals of the igneous rocks will be very small, while if the magma cools off very slowly, than the size of the crystals of the igneous rocks will be bigger.

This happens because of the time of influence of other factors in the formation of the rock itself. The ones that are on the surface or close to it, cool off very quickly, so there's no time for any significant influences on the rock. The ones that are deeper into the ground, cool off much slower because it is hotter, and also in that period the temperature and the high pressure manage to heavily influence the rock, thus making it having bigger crystals.