Read the short text. Read the question and choose the correct answer.

Sleep is a condition of your body and mind in which a nervous system is relatively inactive. Your eyes are closed, muscles are relaxed, and consciousness is mostly suspended for several hours. There are 24 hours in one day, there are 168 hours in a week, and there are 8,760 hours in a year. The average amount of sleep, which many people get each day, should be about 8 hours. It is one-third of a day. If you live 90 years old, you will sleep for 30 years in your life. Every living thing needs to sleep and to rest.

What is sleep, according to the text?

• It is a condition of your body and mind in which your nervous system isn't active.
• It is a condition of your body and mind in which your muscles are tense.
• It is a condition of your body and mind in which your consciousness is clouded.
• It is a condition of your body and mind in which your eyes are tired.