One atomic mass unit has a mass of 1.6605 x 10-24 g. What is the mass of one molecule of H2O?

a. 2.991 x 10-23 g
b. 1.6605 x 10-24 g
c. 6.022 x 1023 g
d. 1.6605 x 10-24 u
e. 18.016 g