Final answer:
The Geatish warrior who died aiding the Danes is Beowulf, the main character of the Old English epic poem. He perishes after his final battle against a dragon, with only his loyal warrior Wiglaf by his side.
Step-by-step explanation:
The Geatish warrior who died while helping the Danes is Beowulf. He is the titular character of the Old English epic poem of the same name. In the poem, Beowulf comes to the aid of Hrothgar, the king of the Danes, whose hall has been under attack by the monster Grendel. After Beowulf slays Grendel and later Grendel's mother, he returns to Geatland and eventually becomes king.
Many years later, Beowulf faces his final battle against a dragon. In this battle, all of his warriors desert him except for one, Wiglaf. Beowulf kills the dragon but is mortally wounded in the process and dies. Therefore, the correct answer to the question is option (a) Beowulf.