In which zone can rooted plants be expected to be found attached to the seafloor? what is the name of this zone and why are plants found there?

Rooted plants (seaweed) would be found close to the shore in the intertidal zone, called the littoral zone. Seaweed is found here as the water here is shallow, and seaweed requires sunlight for photosynthesis, so the water cannot be too deep for the sunlight to penetrate. Seaweed is not a plant as such but rather may belong to one of several groups of multicellular algae.

The answer would be dogs.