Concept:
Each successive letter increases by one additional step.
Step 1: Analyze the first relation.
\[
A \to B \quad (+1)
\]
\[
B \to C \quad (+1)
\]
\[
B \to F \quad (+4)
\]
Step 2: Apply the pattern.
\[
C \to D
\]
\[
D \to E
\]
\[
L \to Q
\]
because
\[
L(12)+5=Q(17).
\]
Therefore
\[
CDL \to DEQ.
\]
Hence the answer is
\[
\boxed{DEQ}.
\]