The addition of a proton to the sulfur atom has resulted in the formation of an isotope. Thus, option A is correct.
The addition of a proton to the nucleus has been resulted in the change in the atomic mass of the element without changing the atomic number.
The atomic mass has been the number of protons and neutrons present in the nucleus. The ions have been resulted when there has been a change in the number of electrons in the atom.
The isotopes have been the element that has been considered of the same atomic number with different atomic masses. The addition of a proton to the sulfur atom changes its atomic mass and thereby forms the isotope of sulfur. Thus, option A is correct.
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