Hi Alex,
I think your answer is (<span>a seafloor that was geologically active with earthquakes, volcanoes, and mountain chains) Good luck!
:)</span>
The answer is b. hot spots
The average mass of one H2O molecule is 18.02 amu. The number of atoms is an exact number, the number of mole is an exact number; they do not affect the number of significant figures. The average mass of one mole of H2O is 18.02 grams. This is stated: the molar mass of water is 18.02 g/mol.
Explanation: