Answer:
Cheerful
Explanation:
Sullen means gloomy or in a bad mood. However, cheerful is the opposite (or an antonym) becuase it is an adjective that means to be happy and in a good mood.
Since the word <em><u>sullen</u></em> means sad or gloomy, the answer is <u><em>cheerful</em></u>.
20 years oldAnswer:
Olivia's garden