Answer:
C. (She sighs softly)
Step-by-step explanation:
Prancing or smiling don't fit the idea of being in love with someone who doesn't feel the same. Being confused also seem not to be the best way, since the character knows exactly what the situation is. A hopelessly in love character will most likely be thinking about what can be done to change the situation and won't be able to think of anyone but the loved one. This can be well represented by a soft sigh.