Step 1: Recall the purpose of elevons.
Elevons are aircraft control surfaces used mainly in tailless aircraft such as delta-wing aircraft.
They combine the functions of
\[
\boxed{\text{Ailerons}}
\]
and
\[
\boxed{\text{Elevators}}.
\]
Step 2: State the functions of the combined control surfaces.
• Ailerons control the rolling motion of the aircraft.
• Elevators control the pitching motion of the aircraft.
An elevon performs both these functions simultaneously.
Therefore,
\[
\boxed{\text{Elevons combine the functions of ailerons and elevators}.}
\]
Thus,
\[
\boxed{(B)}
\]
is the correct answer.