The atoms, in which the number of protons is same but the number of neutrons is different, are known as –

Correct option is D

​The Isotopes are a set of nuclides/atoms having the same number of protons, but a different number of neutrons. In other words, the same atomic number but having different atomic mass. Each individual isotope has a separate nucleus. The Isotopes that are unstable and undergo radioactive decay are called radioisotopes.