The correct answer is: A. Either 0 or 1, between 0 & 1.
In traditional set theory, an element is either in a set or it is not. There is no in-between. This is represented by the truth values 0 and 1, where 0 means “not in the set” and 1 means “in the set.”
In fuzzy set theory, an element can be partially in a set. This is represented by a truth value between 0 and 1, where 0 means “not in the set at all” and 1 means “completely in the set.”
For example, consider the set of “tall people.” In traditional set theory, someone is either tall or they are not. There is no in-between. However, in fuzzy set theory, someone can be “tall to some degree.” For example, someone who is 6 feet tall might be considered “tall” with a truth value of 0.9, while someone who is 5 feet 6 inches tall might be considered “tall” with a truth value of 0.7.
Fuzzy set theory is a more realistic way of representing the world around us, as many things are not black and white. Instead, they exist on a spectrum of possibilities.