Which agent of metamorphism can cause the overall composition of the rock to change?

a. hydrothermal solutions

b. heat

c. pressure

d. time?

The correct answer would be A. The agent of metamorphism that would cause for the overall composition of a rock to change would be hydrothermal solutions. These solutions contain mineral substances that are dissolved in the hot water. When in contact with a rock, the minerals may change the composition of the rock.

The correct answer is (a)