Q.

The magnetic field inside the solenoid is:

1 non-uniform  
2 variable  
3 same at all points  
4 zero  

Ans.

(3)

The magnetic field inside the solenoid is same at all points. This is because the magnetic field lines inside the solenoid are in the form of parallel straight lines, which indicates that the magnetic field is uniform at all points inside the solenoid.