In a mass spectrum of a pure elemental sample, which feature is used to identify the most abundant isotope of the element?
a) the peak that appears at the smallest m/z value (furthest left)
b) the peak that appears at the largest m/z value (furthest right)
c) the peak with the greatest relative intensity (tallest peak)
d) the peak whose m/z is numerically closest to the average atomic mass listed on the periodic table