Two glasses can hold the same amount of liquid. Glass A is 1/2 filled and glass B is 1/3

Two glasses can hold the same amount of liquid. Glass A is 1/2 filled and glass B is 1/3 filled. If the liquid in Glass B is poured into Glass A, what fraction of Glass A will then be filled?
A 5/6B 4/5C 3/4D 1/5