Option A: It is wrong as there is no information of benefits of studying an exam in given paragraph. Option B: The paragraph does not give information about efficiency of student. Hence this option is also incorrect. Option C: This option is correct as it explains about importance of sleep and adequate sleep is a part of preparation. Option D: This option is incorrect as if a student is extremely well prepared for the exam, he needs little or no sleep, this information is not achieved from the given passage.