In the context of Beethoven's "Symphony No. 5," the correct identification is:
A is the motive because it is a short pattern. B is the theme because it is the longer melody of the piece.
The motive typically refers to a brief, distinctive musical idea (often just a few notes), while the theme is a longer, more developed melody that can incorporate or expand upon that motive. In this case, A serves as a recognizable short pattern, characteristic of the symphony, and B presents the fuller thematic material.