Question

life cycle of a star

Explanation:

Step1: Map Sun-sized star path

Cloud of gas and dust (nebula) → Protostar → Main Sequence Star → Red Giant → Planetary Nebula (implied missing step) → White Dwarf → Black Dwarf

Step2: Map massive star path

Cloud of gas and dust (nebula) → Protostar → Main Sequence Star → Red Supergiant → Supernova → Branch 1: Neutron Star; Branch 2: Black Hole

Answer:

Sun-sized star life cycle (left column):

1. Cloud of gas and dust (nebula)
2. Protostar
3. Main Sequence Star
4. Red Giant
5. [Planetary Nebula (implied empty box)]
6. White Dwarf
7. Black Dwarf

Massive star life cycle (right column):

1. Cloud of gas and dust (nebula)
2. Protostar
3. Main Sequence Star
4. Red Supergiant
5. Supernova
6. Neutron Star
7. Black Hole