Final answer:
Scientists look to the ocean floor to research the mantle because it provides access to samples of upper mantle material and helps understand plate tectonics driven by convection in the mantle.
Step-by-step explanation:
Scientists look to the ocean floor to research the mantle because it provides access to samples of upper mantle material. These samples are occasionally ejected from volcanoes, allowing for a detailed analysis of the mantle's chemistry. Additionally, studying the ocean floor helps scientists understand plate tectonics, which is driven by convection in the mantle.