Answer:
A: The artist splashed not only her canvases but also the floor.
Explanation:
The sentence in option A is the best version, which avoids faulty parallelism because it states that two related things happend and caused a surprise or shock. The artist splashed her canvases and the floor (one verb, one action). In B, she splashed... and got paint on the floor(splashed): faulty parallelism. In C, she splashed...the floor was splattered (the artist and the floor): faulty parallelism.