Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in

(A) G1.

(B) G2.

(C) prophase.

(D) metaphase.

(A) G1.

Explanation:

The cell cycle consists of the following stages:

1. G1

2. S (synthesis)

3. G2

4. M (mitosis)

4.1 Prophase

4.2 Metaphase

4.3 Anaphase

4.4 Telophase

5. Cytokinesis

During the S phase the DNA replicates and the chromosome number doubles. For the rest of the cell cycle until cytokinesis, the DNA amount will be double that contained before S, in the G1 phase.