Nuclides which have same mass number are called-

Correct option is B

Nuclides that have the same mass number (sum of protons and neutrons) but different atomic numbers (number of protons) are called isobars.
Isobars have different chemical properties because they have different numbers of protons and electrons, but their nuclear mass remains the same. For example, Carbon-14 and Nitrogen-14 are isobars.