Answer:
Geosphere
Step-by-step explanation:
the continents are not hydrosphere or atmosphere, they are the geosphere. If you look closely into the question you can see that it talks about the ocean floor, not the ocean so atmosphere and hydrosphere are out. There is biosphere on the ocean floor and the continents, but bioshere is all living things and plants! At first i thouht it was biosphere, but then i realized that the ocean floor is made up of rocks, sand, and other minerals(geosphere), so it had to be geosphere, the same with the continents!