Can you help me with percent abundance??

Percent abundance is the percentage of all the different isotopes of an element and is used to calculate the average atomic mass. For example 99.98% of all Hydrogen in the universe is meaning hydrogen with 1 proton and 0 neutrons while the remaining 0.02% is   meaning that is the most abundant by  percent.

the answer would be c

because u need two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei to form isotopes.

so since they all have the same shape? i mean maybe because m& m and reeses are both chocolates