What are temporary dark spots on the Sun's surface called?

Temporary dark spots on the Sun's surface are known as sunspots. These are areas where the solar activity is less intense, resulting in lower temperatures compared to the surrounding regions. Sunspots appear darker because they have a temperature that is considerably cooler than the Sun's outer layer, or photosphere.

Sunspots form in groups and can vary in size and lifespan. They are associated with the Sun's magnetic field and can influence solar phenomena. When sunspots become particularly active, they can lead to various solar events, such as solar flares and coronal mass ejections, which have effects on space weather and can impact satellites and communication systems on Earth.

The other options refer to different phenomena. A solar flare is a sudden and intense brightening on the Sun's surface, resulting from magnetic activity. A black hole is an astronomical object with a gravitational pull so strong that nothing can escape its grasp, unrelated to the Sun's surface features. A solar prominence is a large, bright feature extending outward from the Sun’s surface, often associated with solar flares but is distinct from sunspots. Thus, the definition and characteristics of sunspots make them the correct answer to the question.