During which phase do the chromosomes make copies of themselves so that there are two of each one?

The beginning and majority of the time is known as Interphase. Interphase is 80% of the total cycle and is where the cell does most of the work in replicating organelles, chromosomes, and preparing to undergo Mitosis which is the actual splitting process where one cell becomes two. During Interphase there are 3 major steps, G1, S, and the G2 phase.

Explanation:

the actual answer was 160934