The correct answer is answer choice A, 'In predation the predator usually kills its prey, whereas in parasitism the parasite does not usually kill its host'. While parasites can occasionally kill their hosts, it is more beneficial for the parasite to keep its host alive so that it can continue surviving off of the nutrients it gathers. Answer choice B is incorrect because the prey in predator-prey relationships and the host in parasitism do not benefit. Answer choice C is incorrect because the host does not benefit in parasitism, and is often harmed by the parasite. Answer choice D is incorrect because a predator usually kills its prey, while a parasite usually does not kill its host.
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