An element has two stable isotopes:

Isotope 1: mass = 13.00 amu, abundance = 1.07%
Isotope 2: mass = 12.00 amu, abundance = 98.93%
What is the average atomic mass of this element?

a) 12.01 amu
b) 12.83 amu
c) 12.93 amu
d) 13.00 amu