What element begins fusion in the core immediately after the initial hydrogen fuel in the very center is exhausted?

Answer

Helium

Once the core hydrogen fuel is depleted, the star leaves its initial phase and begins burning helium, provided the gravitational crush heats the core past the necessary ignition threshold.

What element begins fusion in the core immediately after the initial hydrogen fuel in the very center is exhausted?
Elementhydrogencompositionstarsupergiant