Answer:
A. mass X to moles X to moles Y to liters Y
Explanation:
Remember: moles are the great converter. They're basically just a made-up concept meant to facilitate conversions!
Starting with mass X, you must then convert to moles X.
Once you have moles X, convert  moles Y. Think of a chemical equation: the mole ratios are the coefficients!
Once you have moles Y, all you have to do is convert to liters Y. You can do this with the molarity equation M = mol/L, or if it's a gas at STP you know the conversion!
