Convert into indirect speech: 'Let us go out for a walk,' said Ravi.

1. ক
   Ravi proposed that we should go out for a walk.
   
2. খ
   Ravi suggested that they should go out for a walk.
   
3. গ
   Ravi said that let us go out for a walk.
   
4. ঘ
   Ravi proposed to go out for a walk.