Which among the following statements about bio fertilizers are correct?
1. Azotobacter is one of the Nitrogen fixing bacteria used as a bio fertilizer.
2. They have to be applied to the leaves of the plant only.
3. They alter the chemical composi tion of the soil.
4. They can be used along with organic fertilizers.
Select the correct answer using the code given below:

Options

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