Questions: When does cytokinesis begin?

The answer is the first one: late anaphase.

Explanation for each option:

1. Late anaphase: Correct. Cytokinesis typically begins during late anaphase when the chromosomes have been separated and are moving towards opposite poles of the cell. The process of cytokinesis continues through telophase and completes after the chromosomes have been fully separated.

2. Late prophase: Incorrect. During late prophase, the chromosomes are condensing, and the mitotic spindle is forming. Cytokinesis does not begin at this stage.

3. Late interphase: Incorrect. Interphase is the phase where the cell prepares for division by replicating its DNA and organelles. Cytokinesis does not occur during interphase.

4. Late telophase: Incorrect. By late telophase, cytokinesis is already well underway or nearly complete. Telophase is the stage where the nuclear envelope re-forms around the separated chromosomes.

Summary: Cytokinesis begins in late anaphase, as the cell starts to divide its cytoplasm and organelles to form two daughter cells.