Question

the chromosomes shorten and thicken, becoming visible, during ______.
a) metaphase
b) telophase
c) anaphase
d) prophase

Explanation:

To solve this, we analyze each phase of mitosis:

• Metaphase (A): Chromosomes align at the equator, not shortening/thickening here.
• Telophase (B): Involves nuclear envelope reformation, not chromosome condensation.
• Anaphase (C): Sister chromatids separate, chromosomes are already condensed.
• Prophase (D): Chromosomes condense (shorten, thicken) and become visible as the nuclear envelope breaks down.

Answer:

D. prophase