Periwinkle snails, which feed on various types of algae, are thought to be keystone species of rocky northeastern Atlantic shores. This is because Select one: a. Periwinkles eliminated the dominant algae entirely. b. Periwinkles eliminated all algae and died out. c. The action of periwinkles made one type of algae less dominant, which allowed other algae populations to continued. Periwinkles eliminated all of the less-dominant algae species