7. Given that the five-digit number $2018 U$ is a multiple of 9. Then the remainder when this number is divided by 8 is ( ).
(A) 1
(B) 3
(C) 5
(D) 6
(E) 7
7. B.

From the fact that this number is a multiple of 9, we know that the sum of its digits is a multiple of 9, i.e., $2+0+1+8+U$ is a multiple of 9. Therefore, $U=7$.
Since 20000 is a multiple of 8, the remainder when 187 is divided by 8 is 3.