Final answer:
The bard sings about a battle between the Geats and the Swedes as depicted in the epic poem Beowulf, which is part of the larger history of Norse and Germanic peoples' raids and settlements.
Step-by-step explanation:
The bard sings about a battle between two groups of people which, according to the context of raids and settlements of the Norse and Germanic peoples, are most likely the Geats and the Swedes (c).
The Norse peoples, including these two groups, were part of the larger Viking culture that explored, traded with, and sometimes raided various parts of Europe from Scandinavia starting in the 8th century CE. The epic poem Beowulf, which is the work most likely referred to by the question, is set in a time when these Germanic tribes were very active and often in conflict.