Final answer:
Gamma ray bursts are extremely energetic explosions that produce a huge amount of gamma rays.
Step-by-step explanation:
Gamma ray bursts are extremely energetic explosions that release a huge amount of gamma rays. Most of the gamma-ray bursts that our satellites detect are long-duration bursts, which are associated with massive stars that explode as supernovae. These blasts are among the most luminous events in the universe and are observed coming from distant galaxies that are actively forming stars.
The statement that is not true is d) Gamma ray bursts were originally discovered by satellites designed to look for signs of nuclear bomb tests on Earth. In fact, gamma ray bursts were first discovered by satellites designed to detect and study cosmic gamma rays in space.