A is the only logical answer
Isotope has 57.40% abundance
the other one 100% - 57.40% = 42.60%
mass of 121 (% abundance) + mass of 123 (% abundance) = total mass (atomic weight)
(120.9038 amu)(0.5740) + (x amu)(0.426) = 121.76 amu
x = 122.9136
hope this help
Meteor maybe?
I’m pretty sure it’s meteor but if not sorry
