Final answer:
The number of neutrons in hydrogen isotopes ranges from zero to two, depending on whether the isotope is protium, deuterium, or tritium.
Step-by-step explanation:
The number of neutrons in a hydrogen isotope can be zero, one, or two. These isotopes are named as follows: hydrogen (protium) has no neutrons, deuterium has one neutron, and tritium has two neutrons in their respective nuclei. Hence, the answer depends on which hydrogen isotope we are referring to. If we are considering the most common hydrogen isotope, then the correct answer would be (a) 0. For deuterium, the answer would be (b) 1, and for tritium, the answer would be (c) 2.