The correct possible sequence in the life cycle of a massive star is:
nebula, protostar, star, super red giant, supernova, neutron star (or black hole)
This sequence represents the formation and evolution of a massive star:
- Nebula - A cloud of gas and dust where stars are born.
- Protostar - The stage where the cloud collapses under gravity and begins to form a star.
- Star - The main sequence phase where hydrogen is fused into helium.
- Super Red Giant - The phase where the star expands and cools after hydrogen burning.
- Supernova - The explosive end of a massive star's life cycle.
- Neutron Star (or Black Hole) - The remnant left after a supernova, depending on the mass of the original star.
Thus, the closest match to this sequence is:
nebula, protostar, star, super red giant, supernova, neutron star.