Excerpt: "I[the monster] grasped his throat to silence him[William], and in a moment he lay dead at my feet. I gazed on my victim, and my heart swelled with exultation and triumph: clapping my hands, I exclaimed "i too can create desolation."
The answer is option D
By describing such act of violence, performed by the monster to someone else, and how the monster relishes to do it, the author is trying to evoke within the reader a feeling of anxiety and fear that something bad and abominable is about to happen. And it happened. The last words of the monster insinuate that it may continue to cause damage, leaving the reader with the same feeling.