Question

which is the final event that occurs when a star is forming? the outer layer of the star expands. gravity pulls gas and dust together. a black hole forms as the core collapses. nuclear fusion begins under high pressure.

Explanation:

During star - formation, gravity first pulls gas and dust together. As the core contracts, temperature and pressure increase. The final event that marks a star's birth is the start of nuclear fusion in its core. Outer - layer expansion occurs later in a star's life cycle, and black - hole formation is not part of the star - forming process but of a massive star's death.

Answer:

Nuclear fusion begins under high pressure.