<span>C. Están corriendo is the answer.
There you go.</span>
All of them involve winter so D. is the answer
the only difference between –er verbs and –ir verbs is the nosotros and vosotros forms.
<u>Example: Vivir (to live)</u>
<u>Nosotros:</u> vivimos
<u>Vosotros: </u>vivís
<u>Example: Volver (to return)</u>
<u>Nosotros:</u> volvemos
<u>Vosotros:</u> volvéis
