7. Let $z$ be a six-digit positive integer, where the first three digits are the same as the last three digits and in the same order (for example, 247 247). Which of the following numbers ( ) must be a divisor of $z$.
(A) 11
(B) 19
(C) 101
(D) 111
(E) 1111
7. A.

According to the problem, let $z=\overline{a b c a b c}$. Then $z=1001 \times \overline{a b c}=7 \times 11 \times 13 \times \overline{a b c}$.