I would say it's a simile because they are comparing with using the word "like". They are comparing there howling to the wolves.
From the choices D would appear to be the best.
A writer should use a reciprocal pronoun when:
B. two or more subjects of the sentence are also objects.
<u>Reciprocal pronouns</u> (<em>each other</em> and <em>one another</em>) are used to indicate that two or more people are carrying out a given action. A writer should use them as objects when they have already been mentioned as subjects. For example:
<em>Gary and July could not wait to give the presents to </em><em>each other</em><em>. </em>
