Consider the following statements and select the correct answer using the code given below: 1. The stabilization of the atmosphere took place around 600 million years back. 2. The rate of solar constant is 1.968 calories per cm per minute. 3. The solar constant is measured at the outer limit of the atmosphere.

• A. 1, 2 and 3 are correct    
• B. 1 and 2 are correct
• C. 1 and 3 are correct     
• D. 2 and 3 are correct