The Space Shuttle Uses Liquid Hydrogen and Liquid Oxygen to Produce

Multiple Choice

The space shuttle uses liquid hydrogen and liquid oxygen to produce thrust for liftoff in the following reaction. If the liquid oxygen supply is set to provide 420 kg/s during a launch, what does the rate of liquid hydrogen supply need to be in kilograms per second?
2H₂(l) + O₂(l) $\rightarrow$ 2H₂O(g)

A) 840 kg/s
B) 210 kg/s
C) 106 kg/s
D) 52.9 kg/s
E) 63.4 kg/s