Question

Which of the following is the stage where a massive star explodes and releases a lot of energy $?$
(A) Red supergiant
(B) Blackhole
(C) Main sequence
(D) Supernova

Answer 1

Hint : Massive stars transform into supernovae, neutron stars and black holes. While average stars like the sun, end life as a white dwarf surrounded by a disappearing planetary nebula. All stars, irrespective of their size, follow the same $7$ stage cycle, they start as a gas cloud and end as a star remnant.
Seven main stages of a Star
1. Giant Gas Cloud
2. Protostar
3. T-Tauri Phase
4. Main Sequence
5. Red Giant
6. The Fusion of Heavier Elements
7. Supernovae and Planetary Nebulae

Complete Step By Step Answer:
All red supergiants will exhaust the helium in their cores within one or two million years and then start to burn carbon. This continues with fusion of heavier elements until an iron core builds up, which then inevitably collapses to produce a supernova.
A supernova is a powerful and luminous stellar explosion. This transient astronomical event occurs during the last evolutionary stages of a massive star or when a white dwarf is triggered into runaway nuclear fusion.
At the supernova stage (Stars with very large masses) most of the star material is blasted away into space, but the core implodes into a neutron star or a singularity known as the black hole. Less massive stars don’t explode. A black hole releases a huge amount of gravitational energy, as material swirls toward its event horizon.
The main sequence is the stage where the core temperature reaches the point for the fusion to commence. In this process, the protons of hydrogen are converted into atoms of helium.
Hence, the correct Option is D. Supernova.

Note :
Sirius, also known as the Dog Star or Sirius A, is the brightest star in Earth's night sky. Red dwarfs are considered the smallest stars known that are active fusion stars, and are the smallest stars possible that are not brown dwarfs. This star is slightly smaller than Saturn. The largest known star (in terms of mass and brightness) is called the Pistol Star.