Which answer best summarizes the events from the poem contained in the following lines?

"then came to the building the warrior marching,
bereft of his joyance. the door quickly opened
on fire-hinges fastened, when his fingers had touched it;
the fell one had flung then—his fury so bitter—
open the entrance."

a. beowulf opens the door of the mead-hall and finds grendel waiting.

b. grendel arrives and rips open the door of the mead-hall.

c. beowulf keeps the door of the mead-hall closed as grendel tries to enter.

d. grendel tries to break down the door of the mead-hall but fails.