Within the deep interior of the Sun, which development will eventually lead to major changes as the Sun evolves off the main sequence toward the red giant phase of its life?
A)expansion of the core by the buildup of hydrogen in the nuclear furnace, pushing the outer regions of the Sun outward
B)the supernova explosion that will occur when the buildup of helium in the core exceeds a certain critical amount
C)slowing down of the nuclear furnace as the central core temperature drops with time
D)buildup of inactive helium by the transformation of hydrogen in the thermonuclear furnace

Question

Quizplus · Accepted Answer

The buildup of inactive helium in the core, resulting from the fusion of hydrogen in the Sun's thermonuclear furnace, leads to a decrease in nuclear fusion reactions in the core. This causes the core to contract under gravity, which in turn heats up the core and the surrounding shell of hydrogen, leading to an expansion of the outer layers of the Sun and its evolution toward the red giant phase.

Within the Deep Interior of the Sun, Which Development Will