Aristotle wrote:
\[
\textit{Poetics}.
\]
So statement A is correct.
Longinus is associated with:
\[
\textit{On the Sublime},
\]
not On Imitation.
So statement B is incorrect.
Plato's Republic does not celebrate poets as guides of truth.
Rather, Plato criticizes poetry and imitation.
So statement C is incorrect.
Horace wrote:
\[
\textit{Ars Poetica}.
\]
So statement D is correct.
Aristotle discussed catharsis in relation to tragedy, not only comedy.
So statement E is incorrect.
Therefore, the correct statements are:
\[
A\ \text{and}\ D\ \text{Only}.
\]