Final answer:
a. Dr. Jekyll. The character who said this quote is Dr. Jekyll.
Step-by-step explanation:
The correct answer is a. Dr. Jekyll. In the novel Dr. Jekyll and Mr. Hyde by Robert Louis Stevenson, Dr. Jekyll says this quote. It reflects his inner struggle and the pleasure he finds in indulging in his darker side as Mr. Hyde. This quote highlights the theme of duality and the conflict between good and evil within a person.