Please answer the following question: Read the following article and select the best answer. Article: During the day we work and play; at night we sleep. Our bodies rest while we sleep. In the morning we are ready to work and play again. While we are asleep our bodies grow most. Children usually need more sleep. We can get our lessons better and we feel better too, when we have plenty of rest. Boys and girls need ten hours of sleep every night when they are eight or nine years old. Our bodies need lots of air when we sleep. If we do not get enough fresh air we'll feel tired when we wake up. While in bed we must not cover our heads. If we do, our lungs will not get enough fresh air. If we open our windows at night we can have plenty of fresh air. Cool air is better then warm air. Boys and girls must get enough sleep if they want to grow and be strong. Question: What do the lungs need most? - Fresh air - Food - Rest - Exercise
Answer:
Fresh air