Answer:
In a stable star, the force of nuclear fusion is balanced by the force of gravity. The high temperatures and pressures in the core of the star cause atoms to collide and fuse together, releasing energy in the process. This energy is what keeps the star from collapsing under the force of gravity. The outward pressure from the energy released by nuclear fusion pushes outward, while the force of gravity pulls inward. In a stable star, these two forces are balanced, with the inward force of gravity being counteracted by the outward pressure from fusion. This balance allows the star to maintain a stable size and temperature.
Therefore the answer is A. outward, inward.