Look at the minerals shown below. An image showing uranium and copper.
Uranium: © 2010 Kgrr Creative Commons
Copper: © 2010 Daniel Stucht Creative Commons

Both uranium and copper are formed by the process of crystallization. Which of these is a step in the formation of the minerals?

elements combine due to high pressure
water solidifies due to drop in temperature
atoms break up after a chemical reaction
magma cools after a volcanic eruption