The correct answer is B) They were rivals for Helena.
Hermia thinks that Demetrius has killed Lysander because they were rivals for Helena.
We are referring to a moment of the play "Midsummer Night's Dream" written by William Shakespeare in 1595. In this comedy, Shakespeare depicts the marriage of Theseus to Hippolyta.
In the part of the played referred by the question, Hermia thinks Demetrius killed Lysander because both were rivals pretending the love of Helena. Indeed, Demetrious challenges Lysander to a duel to gain the love of Helena.
