Concept:Parentheses are used to add extra information. Common phrases like "all day" should not be hyphenated or written as one word.Explanation:Option A correctly places parentheses around "all day" to add clarifying detail.Option B has an unnecessary hyphen in "all-day".Option C incorrectly writes "allday" as a single word.Option D is wrong because Option A is correct.Answer:A. You studied (all day) for the grammar test.