Question

red giants and supergiants are fusing __.

helium into carbon
hydrogen into helium
hydrogen into carbon

Explanation:

Red giants and supergiants are stars that have exhausted the hydrogen in their cores. After the hydrogen - burning phase (where hydrogen is fused into helium in the main - sequence stars), in red giants and supergiants, the core temperature and pressure increase enough to start fusing helium. The helium fusion process combines helium nuclei (\(^4He\)) to form carbon (\(^{12}C\)) through the triple - alpha process (\(3^4He
ightarrow^{12}C\)).

• Hydrogen into helium fusion occurs in the main - sequence phase of stars.
• Hydrogen into carbon is not a common fusion process in the context of stellar evolution for red giants and supergiants.

Answer:

helium into carbon