Answer:
C. (She sighs softly)
Step-by-step explanation:
The character is hopelessly in love, but that love is unreturned. She loves the other character, but feels hopeless, which is why she sighs. It wouldn't make a lot of sense for her to be happy, unless she was completely clueless. She might be confused, but the best way to reflect the character's hopeless love is to have her sigh.