Fact 1: Vein deposits of gold and silver are formed by igneous intrusion.

Fact 2: Magma that cools slowly deep below the surface produces coarse-grained intrusive igneous rocks.

Given the two facts above, answer the question "When do vein deposits of gold and silver form?" with the following options: 
- When magma warms up
 - flow of electrons
 - it can be seen
 - permineralization
 - When magma cools
 - aqueous solution
 - When the air is cold
 - When water rises


 

     When magma cools    