The correct answer is C.
It shows that this method is a disadvantage to those who need review at the beginning of the year.
This option highlights a potential drawback of year-round schooling, which contrasts with the assertion in paragraph 3 of "Year–Round Schooling Helps Students, Teachers, and Families," that year-round schooling allows teachers to spend less time reviewing old material. The information from the opposing paragraph implies that not all students may benefit from the lack of review, thus providing a more nuanced view of the effectiveness of year-round schooling.