During which phase of the cell cycle are chromo-
somes copied?

S phase

Explanation:

S phase is the second phase of interphase (longest phase where cell grows and replicates it's DNA and does it function. It is broken up into smaller sub phases). S phase is the synthesis phase. During this phase chromosomes are replicated ( The DNA is copied).

ok yes, but what is the question? as soon as you ask the actual question i will answer it. : )