Which line from Grendel best shows the darker side of the character Beowulf?

After a thorough research, there exists the same question with the following choices.

(A) He paused, his eyebrows cocked, and glanced at the coastguard and smiled

(B) The sea-pale eyes of the stranger were focused on nothing

(C) The stranger smiled on, his downward-slanting eyes like empty pit

(D) The stranger stopped eating, smiled

The correct answer is letter (C) 'The stranger smiled on, his downw ard-slanting eyes like empty pit.' best depicts the darker side of Beowulf.