The correct answer is D. Merriment.
Mirth is a feeling of happiness and enjoyment, often accompanied by laughter. Merriment is a similar feeling, but it is often more intense and may be accompanied by other physical manifestations of joy, such as dancing or singing.
Sorrow is a feeling of sadness or regret. Enthusiasm is a feeling of excitement or eagerness. Adventure is an exciting or unusual experience.
Sorrow is not a synonym of mirth because sorrow is a feeling of sadness, while mirth is a feeling of happiness. Enthusiasm is not a synonym of mirth because enthusiasm is a feeling of excitement or eagerness, while mirth is a feeling of happiness. Adventure is not a synonym of mirth because adventure is an exciting or unusual experience, while mirth is a feeling of happiness.
Merriment is a synonym of mirth because merriment is a feeling of happiness and enjoyment, often accompanied by laughter.