Answer:
A. S phase
Explanation:
The cell cycle involves all the series of division events that occurs to an organism. Cell division, which can be meiosis or mitosis, involves two main stages viz: Interphase and M phase.
Interphase describes the resting stage of the cell i.e. when the cell is not dividing. The cell uses this time to prepare itself for the next round of division. Interphase stage further consists of three main phases viz: G1, S and G2 phases.
In the S phase or synthesis phase of Interphase, the cell duplicates its genetic material (DNA). Hence, an onion cell observed by a student to have loosely coiled chromatin depicting DNA duplication is in the S-PHASE.
