8. Malcolm wants to visit Isabella after school, but he only knows the street she lives on, not her room number. Isabella tells him: “My room number is a two-digit number, and three of the following four pieces of information are true:
(1) The number is a prime number;
(2) The number is even;
(3) The number is divisible by 7;
(4) One of the digits of the number is 9.”
This information allows Malcolm to determine Isabella's room number. The unit digit of the room number is ( ).
(A) 4
(B) 6
(C) 7
(D) 8
(E) 9
8. D.

If (1) is true, that is, this number is a prime number, then this two-digit number must not be even, and it must not be divisible by 7. Therefore, (2) and (3) are not true, which contradicts the condition that only one of the four propositions is false. Thus, (1) cannot be true. Therefore, (2), (3), and (4) are true.
Let this number be $\overline{9 x}(x \in\{0,2, \cdots, 8\})$.
Since this number is divisible by 7, we know $x=8$.
Therefore, this number is 98, and the unit digit is 8.