"Both zoos and reserves attempt to ensure that animals will survive for future generations, but, whether intentionally or not, both habitats potentially harm the animals they seek to protect. To ensure that future generations of animals will escape extinction, the best answer might be neither zoos nor animal reserves but simply for humans to leave animals alone in their natural habitat. At the very least, humans must find an ethical and humane way to preserve all species with which we share the planet." (Folse, 2014, p. 119) The conclusion paragraph above comes from an essay which argues that although zoos and reserves seem to protect animals from extinction, they may, in fact, be jeopardizing the well-being of animals since zoos do not replicate the conditions of the wild and reserves might attract poachers who kill these animals to sell their parts in the black market. Based on this information, which of the following is missing from this paragraph?  单项选择题