There are five friends sitting in a row. Let's represent the positions as ____.
Information given:
Let's combine these pieces of information:
Case 1: D is at the leftmost end.
D ____
Since B is between D and E, the sequence must start D B E:
D B E ____
The remaining two positions must be filled by the pair (A C).
So, the arrangement is: D B E A C.
Let's check if this is consistent with condition 1 (A C together): Yes.
Positions:
In this arrangement, the person in the middle (3rd position) is E.
Case 2: D is at the rightmost end.
____D
Since B is between D and E, the sequence must end E B D (reading from left to right):
__ ___E B D
The remaining two positions must be filled by the pair (A C).
So, the arrangement is: A C E B D. Positions:
In this arrangement, the person in the middle (3rd position) is E. In both valid arrangements, E is in the middle.
\[ \boxed{\text{E}} \]