The two species of human tapeworm can be distinguished by the presence or absence of...

Explanation

This question is asking about how to distinguish between the two species of human tapeworm. The options given are Scolex, hook, head, and sucker. To answer this question, it is important to understand what a tapeworm is. A tapeworm is a type of parasitic flatworm that lives in the intestines of animals, including humans. The tapeworm has a long, flat body made up of segments called proglottids. Each proglottid contains reproductive organs, which allow the tapeworm to produce eggs that can be passed out of the host's body in feces. Now, to distinguish between the two species of human tapeworm, we need to look at the given options. Option A, Scolex, refers to the head of the tapeworm, which is used to attach to the host's intestinal wall. Option C, head, is the same as Scolex and is not a useful distinguishing factor. Option D, sucker, refers to the structures on the tapeworm's body that help it attach to the host's intestinal wall. Option B, hook, is the correct answer. The two species of human tapeworm can be distinguished by the presence or absence of hooks on their scolex. One species has hooks while the other does not. These hooks are used to anchor the tapeworm to the intestinal wall and help it avoid being carried out of the host's body in feces. In summary, the correct way to distinguish between the two species of human tapeworm is to look for the presence or absence of hooks on their scolex. Option B, hook, is the correct answer to this question.