I was struggling with the correct answer (B) and (E). Obviously, (B) is correct, because it points out the assumption that the route that polar bear went is already familiar to them, therefore, it does not meet the criteria (definition) of "navigation". However, I think (E) also points out that "polar bears rely on their extreme sensitivity to smell in order to scent out familiar territory", while in the contextual information, it has been pointed out that Navigation is defined as (1) animal's ability to find its way from unfamiliar territory to points familiar to the animal (2) but beyond the immediate range of the animal's senses. (E) points out the assumption that it is in the range of the animal's sense, because polar bears' extreme sensitivity to smell; therefore weaken the argument.
I saw couple people were struggling with this answer choice for the same reason, could someone help us? I will really appreciate.