Which of the following statements about community interactions is not correct? a) closely related species may be able to coexist if there is at least one significant difference in their niches. b) plants can defend themselves against herbivores by the production of compounds that are irritating or toxic. c) keystone predators reduce diversity in a community by holding down or wiping out prey populations. d) mutualism is an important biotic interaction that occurs in communities. e) some predators use mimicry to attract prey.