Final answer:
Hrothgar's explanation in lines 1325-1333 refers to Grendel's attacks and the sorrow they caused in his kingdom, which ties into the historical events of the time. a. Historical events
Step-by-step explanation:
In lines 1325-1333 of the poem Beowulf, the aspect of Hrothgar's explanation referred to is c. Grendel's attacks.
These lines are part of Hrothgar's speech on how Grendel's nocturnal assaults have caused great sorrow and despair in his kingdom, reflecting the poem's themes of heroism in the face of adversity and the struggle between good and evil. Through Hrothgar's lament, the poem provides insight into the historical events of the time, merging authentic oral history with the legend of Beowulf's battle against the monster Grendel.