The atomic symbol mc026-1.jpg represents lead-206 (Pb-206), an isotope that has 82 protons and 124 neutrons. Which atomic symbol could represent an isotope that undergoes radioactive decay to produce

The atomic symbol mc026-1.jpg represents lead-206 (Pb-206), an isotope that has 82 protons and 124 neutrons. Which atomic symbol could represent an isotope that undergoes radioactive decay to produce Pb-206?

1.238U

92

2.222Pb

87

3.178Hf

72

4.192Pb

77