6. $A, B, C, D, E$ are sitting in a small train with 5 carriages, with each carriage seating only one person. It is known that $D$ is sitting in the last carriage, $A$ is next to $E$ but behind $E$, $B$ is sitting in the carriage in front of $A$, and there is at least one person between $C$ and $B$. Then $(\quad)$ is sitting in the middle position.
(A) $A$
(B) $B$
(C) $C$
(D) $D$
(E) $E$
6. A.

Let the order of the carriages be denoted as $\square \square \square \square \square$, where the leftmost position represents the first carriage, and the rightmost position represents the last carriage.
From the first condition, we know $\square \square \square \square D$.
From the second condition, we know it must be one of the following three cases:
$\square \square E A D, \square E A \square D, E A \square \square D$.
(1) From $B$ being in front of $A$, we know the arrangements are $C B E A D$ and $C B E D A$, neither of which satisfies the last condition;
(2) The arrangement $B E A C D$ satisfies all conditions;
(3) Clearly, it does not satisfy $B$ being in front of $A$.
Therefore, the only order that meets all conditions is BEACD, meaning the person sitting in the middle position is $A$.