The begonia and the ranunculus have somewhat similar blooms, but very different foliage. Begonias tend to have much broader, darker leaves, while the ranunculus has smaller and almost curly leaves. Here is a better pic of it:
Photograph of a Ranunculus in Bloom You can tell in the picture in the OP that the foliage matches that of the ranunculus, plus the blooms are on longer stems, where begonias are closer to the base of the plant. Not trying to be argumentative, I am just an avid gardener. I could be wrong, there could be another kind of begonia that has different foliage that I haven't seen
