Which statement describes how the Sun makes energy?

• A. Nuclear fusion occurs in the core producing energy.
• B. Chemical burning of hydrogen in the photosphere.
• C. Nuclear fusion in the core turning hydrogen into helium and releasing energy.
• D. The Sun converts mass to energy only during solar flares.

Answer: (C)

The Sun shines because nuclear fusion in its core converts hydrogen into helium, releasing energy. In the extreme temperatures and pressures at the center, hydrogen nuclei fuse through fusion reactions, primarily the proton‑proton chain, and a small amount of mass is converted into energy according to E=mc^2. This energy starts as high‑energy photons and neutrinos, and it gradually works its way outward, eventually escaping as the sunlight we receive.

This explanation is more complete than saying fusion simply “occurs in the core,” because it specifies both the fuel (hydrogen) and the product (helium) and notes that energy is released in the process. The idea of chemical burning in the photosphere is incorrect because chemical reactions do not power the Sun; chemical energies are far too small at stellar temperatures. The notion that mass is converted to energy only during solar flares is also false—the fusion energy source operates continuously, not just during flares.