Read the following paragraph from the section "The Conveyor Bolt." Scientists have long understood how nutrients move from the ocean's surface to its dopths. As phytoplankton die, they sink and collect on the ocean floor. But if nutrients are continually sinking to the depths of the ocean, how are surface waters replenished with nutrients? Scientists discovered that in certain regions of the ocean, the nutrient-rich doop water was upwelling, or rising to the surface. Which phrase from the paragraph helps you to understand that ocean hoalth Involves steady restoration? (A) move from the ocean's surface (B) collect on the ocean floor (C) replenished with nutrients (D) nutrient-rich deep water
