The correct answer to the question "Why do sunspots look darker than the rest of the sun's photosphere?" is:
C. Sunspots are cooler than the surrounding areas.
Explanation:
1. Sunspots appear darker because they are cooler than the surrounding photosphere of the sun.
2. The photosphere is the visible surface of the sun where most of the sunlight we see originates.
3. Sunspots are regions on the sun where magnetic fields are concentrated, inhibiting the convective transfer of heat, making them cooler.
4. Cooler regions emit less light and energy compared to the hotter regions, hence appearing darker in contrast to the brighter surrounding photosphere.
5. This temperature difference between the sunspots and the surrounding areas contributes to their darker appearance.
Understanding that sunspots are cooler areas on the sun's surface helps explain why they appear darker compared to the surrounding photosphere.
