Which of the following best describes the reaction seen below?

2H2(g) + O2(g) → 2H2O(l)

a.
Two grams of hydrogen gas combine with 1 gram of oxygen gas to form 2 grams of water.

b.
Two molecules of hydrogen gas combine with 1 molecule of oxygen gas to form 2 molecules of water.

c.
Two liters of hydrogen gas combine with 2 liters of oxygen gas to form 2 liters of water.

d.
Two hydrogen atoms combine with 1 oxygen atom to form 2 water molecules.