The Sea Otter Acts as a Keystone Species in the Kelp

The sea otter acts as a keystone species in the kelp (giant seaweed) forests of the ocean in the Pacific Northwest.Sea otters feed on sea urchins, which in turn feed on kelp.Crabs, snails, and geese also depend on kelp for food, and many types of fish use the kelp to hide from predators.Sea otter populations are declining in some areas because of increased predation by orca whales.What effect will the decline in sea otters likely have on the kelp community?

A) Little effect, since otters can be easily replaced by other predators.
B) Sea urchin populations will increase, and kelp populations will increase to provide more food for them.
C) Community diversity will increase, as prey species are no longer threatened by sea otters.
D) Community diversity will decrease as sea urchins overpopulate and overexploit kelp.
E) Sea urchins will overexploit kelp, thinning the habitat and providing room for more fish and invertebrates to move in.