Boron Obtained from Borax Deposits in Death Valley Consists of Two

Multiple Choice

Boron obtained from borax deposits in Death Valley consists of two isotopes. They are boron-10 and boron-11 with atomic masses of 10.013 amu and 11.009 amu, respectively. The atomic mass of boron is 10.81 amu (see periodic table) . Which isotope of boron is more abundant, boron-10 or boron-11

A) Cannot be determined from data given
B) Neither, their abundances are the same.
C) Boron-10
D) Boron-11