Answer:
b. Clean up plastic trash from shorelines, rivers, and other waterways that flow into the oceans.
Step-by-step explanation:
Oceanic plastic garbage "patches" are a build up of debris most especially plastic, nylons, waste from wood that was deposited purposely or not purposely( by the wind or ocean waves) into the ocean.
Human activity that would most directly reduce the amount of plastic garbage that enters the ocean includes the cleaning up plastic trash from shorelines, rivers, and other waterways that flow into the oceans.