Which among the given combinations below represent a set of isotopes?
1.40 protons and 40 neutrons
II. 41 protons and 39 neutrons
3.42 neutrons and 48 protons
4 40 protons and 42 neutrons
V. 41 protons and 40 neutrons
A. I, II, III
B. III, IV
C.1, IV and II, V
D. 1, V and II. V
E.1. V