Final answer:
Grendel is the most clearly a round character in the novel 'Grendel' as he is the main character with complexity and depth, who experiences growth and change, unlike the other characters mentioned.
Step-by-step explanation:
The character in Grendel that is most clearly a round character is d. Grendel.
In literature, a round character is one that is complex, fully developed, and often undergoes changes throughout the story. Grendel fits this description as he is the protagonist and narrator who reflects on his existence, interacts with various philosophical ideas, and has emotional depth. Throughout the novel, Grendel's character evolves as he experiences different emotions, encounters with humans, and philosophical conflicts, making him a multifaceted character with psychological depth, in contrast to other characters who are not as well developed.
Grendel's journey and internal struggle provide depth to his personality, revealing his vulnerabilities, fears, and desires, which are not as apparent in other characters such as Wrolstan, Hrothgar, or Beowulf, who are depicted more straightforwardly.