Biology

The correct answer is: A.By checking for proper spindle attachment at the metaphase plate.

During metaphase, the cell ensures that each chromosome is correctly aligned at the metaphase plate and attached to the spindle fibers from opposite poles. This process is part of the spindle checkpoint. If any chromosome is not properly attached to the spindle, the cell will not proceed to anaphase, preventing errors in chromosome segregation.

Explanation of why the other options are incorrect:

B.By duplicating the chromosomes: Chromosome duplication (DNA replication) occurs before mitosis, during the S phase of the cell cycle, not during anaphas...