What is the closest meaning to "sardonic" in tone?

The term "sardonic" refers to a form of humor that is characterized by a disdainful, mocking, or cynical tone. It often conveys a sense of bitterness and is used to express scorn or derision. Therefore, the closest meaning to "sardonic" in tone is indeed mocking and bitter.

In contrast, the other choices evoke emotions and tones that are positive or warm, which do not align with the essence of sardonic humor. Such tones like joyful and engaged, friendly and warm, or excited and upbeat reflect positivity and friendliness, whereas a sardonic tone inherently carries a critical or sarcastic edge, making the correct interpretation focused on mockery and bitterness.