What reaction fuels a star during its longest life phase, the main sequence stage?

Answer

Fusing hydrogen nuclei into helium nuclei

The main sequence stage is defined by the star fusing hydrogen into helium in its core. This process balances the inward crush of gravity with outward pressure generated by the released energy.

What reaction fuels a star during its longest life phase, the main sequence stage?
Elementstarformationnucleosynthesisastrophysic