Respuesta :
Anwer:
The grim laughter
Explanation
There were signs of the scary atmosphere in the text, the dragon-charm and laughing, whispering. Whispering and trembling are referring that something is going to happen. Even though they indicate possible action, the grim laughter was uncontrollable and surprising.
The laugh was not pleasant and makes the horrifying atmosphere which makes the character is afraid of Grendel. Grim laughter is horrifying because it is unpleasant and unstoppable. It is not happy laughter, it is laughter over the situation in which the character tries to escape. The character describes these creatures like crazy, so grim laughter makes the character uncomfortable, scary and horrifying.