Select from: 1). In their beds; 2). body water; 3). competing for resources; 4). In their shoes; 5). loose soil; 6). In their intestines; 7). important habitats; 8). On their surface;
Given those answer options, answer the question: You are presented with the quiz "Where do leeches live in relation to their hosts?" But you don't know the answer, so you turn to your teacher to ask for hints. He says that "some parasites live on the surface of their host" and "leeches are external parasites". So, what's the best answer to the question?
A:
8).