Consider the following statements about the atmosphere 1. Chemically it is divided into homosphere and heterosphere. 2. Molecular layer extends from 200 to 1100 km. 3. Water vapour present in the air produces the optical phenomena of red and orange hues in the sky at sunrise and sunset which are known as dawn and dusk respectively. 4. Thermosphere is divided into ionosphere and exosphere Which of the above statements are correct?

• A.  2, 3 and 4 only          
• B.  1, 2 and 3 only
• C.  1, 3 and 4 only          
• D.  1, 2 and 4 only