Q. There is a concern : over the increase in harmful algal blooms in the seawaters India. What could be the causative factors for this phenomenon?1. Discharge of nutrients from the estuaries.2. Run-off from the land during the monsoon.3. Upwelling in the seas.Select the correct answer from the codes below : 

1. 1 only
2. 1 and 2 only
3. 2 and 3 only
4. 1,2 and 3