What is trophic cascade as mentioned in this video titled "How Wolves Change Rivers?"

A• how the rivers flow throughout Yellowstone National Park.

B• Ecological process that starts at top of the food chain and tumbles down to the bottom of the food chain.

C•different types of food chains and food webs.

D• Ecological process that starts at the bottom of the food chain and works it way up to the top of the food chain