Without Actually Solving the Problem, Choose the Correct Solution by Deciding

Multiple Choice

Without actually solving the problem, choose the correct solution by deciding which choice satisfies the given conditions.
-Trish has two containers of water for a camping trip. One container holds 2 times as much as the other. The total amount of water is 21 gallons. How much water is in each container?

A) 21 gallons; 7 gallons
B) $7.5$ gallons; $13.5$ gallons
C) 7 gallons; 14 gallons
D) 6 gallons; 15 gallons