Which shows these numbers in order from least to greatest?
7.2 x 109, 7.2 x 108, 7.02 x 108
A 7.2 x 109, 7.02 x 108, 7.2 x 108
B 7.2 x 109, 7.2 x 108, 7.02 x 108
C 7.2 x 108, 7.02 x 108, 7.2 * 109
D 7.02 x 108, 7.2 % 108, 7.2 x 109