The table shows the relative intensities of singly charged lithium ions detected for a natural lithium standard and for Sample B.
Li-6 (m/z 6) Li-7 (m/z 7)
Natural standard 7.6 % 92.4 %
Sample B 28.5 % 71.5 %
By what factor has the percent abundance of Li-6 increased in Sample B compared with the natural standard?
a) 2.75
b) 3.8
c) 0.27
d) 4.9