Explanation
"Facetious" means treating serious issues with deliberately inappropriate humor, so its direct opposite is "Serious." The other options—copy, teasing, and tongue-in-cheek—are either unrelated or similar in meaning to facetious.
Practice this MCQ: What is the antonym of Facetious?. Check correct answer and detailed explanation on MrProfessor.
"Facetious" means treating serious issues with deliberately inappropriate humor, so its direct opposite is "Serious." The other options—copy, teasing, and tongue-in-cheek—are either unrelated or similar in meaning to facetious.