Biology

The correct answer is: B.Chromosomes are replicated.

During the S phase (Synthesis phase) of the cell cycle, the primary event is the replication of DNA, meaning each chromosome is duplicated. This results in the formation of two identical sister chromatids attached at a centromere.

Here's a breakdown of the other options:

A.Chromosomes condense: Chromosome condensation happens later, during prophase, which is part of mitosis. During the S phase, chromosomes are not yet condensed but remain in a more relaxed, extended form for DNA...