Which sequence correctly depicts the early life cycle of a star?

Which sequence correctly depicts the early life cycle of a star?

• A. Protostar → Nebula → Adult star
• B. Nebula → Protostar → Adult star
• C. Nebula → Adult star → Protostar
• D. Adult star → Protostar → Nebula

Answer: (B)

Star formation begins in a nebula, a cloud of gas and dust. Under gravity, parts of the nebula collapse to form a protostar, which continues to gather material. When the core becomes hot enough for hydrogen fusion, it settles into a main-sequence star—that is, an adult star. This sequence—nebula → protostar → adult (main-sequence) star—captures the early life cycle. Starting with a protostar or an adult star would skip or invert essential stages, and placing an adult star before the protostar doesn’t reflect how stars actually form.

Star formation begins in a nebula, a cloud of gas and dust. Under gravity, parts of the nebula collapse to form a protostar, which continues to gather material. When the core becomes hot enough for hydrogen fusion, it settles into a main-sequence star—that is, an adult star. This sequence—nebula → protostar → adult (main-sequence) star—captures the early life cycle.

Starting with a protostar or an adult star would skip or invert essential stages, and placing an adult star before the protostar doesn’t reflect how stars actually form.