Answer: B. Figurative language
Figurative language refers to the use of words in ways that are not meant to be taken literally. It uses words in a way that deviates from their conventional use in order to convey a different meaning or heighten the effect of the speech. In this case, the phrase "to crush him like a fly" does not literally mean that Grendel wants to crush Unferth in the same way as a fly. The statement is not to be taken literally. Instead, it is intended to heighten the feeling of anger and frustration that Grendel feels towards Unferth.