Protium and deuterum only
Protium, deuterium and tritium
Tritium and protium only
Deuterium and tritium only
Hydrogen has three naturally occurring isotopes: 1H (protium), 2H (deuterium), and 3H (tritium). These isotopes form naturally in nature. Protium and deuterium are stable. Tritium is radioactive and has a half-life of about 12 years. Hence, option B is correct.