As the electromagnetic wave is crossed field of electric & magnetic wave...so the direction of propagation of EM wave is the direction of vector E × B .
Here E is upward and (E × B) is toward the north .
So, from right hand thumb rule B will be along east...
So, correct answer is east...

$$Hope it's help... $$

Electromagnetic Wave Propagation and Electric Field Vector

An electromagnetic wave is a transverse wave that consists of an electric field and a magnetic field oscillating perpendicular to each other. These waves propagate through space at the speed of light.

Direction of Propagation and Electric Field Vector

When an electromagnetic wave propagates along a specific direction, the electric field vector of the wave is perpendicular to the direction of propagation. In this case, the wave is propagating along the north direction, so the electric field vector is oriented upwards.

Direction of Magnetic Field Vector

The direction of the magnetic field vector in an electromagnetic wave is determined by the right-hand rule. According to this rule, if you point your thumb in the direction of propagation (north in this case), then your curled fingers will give you the direction of the magnetic field vector.

Application of Right-Hand Rule

In this scenario, when an electromagnetic wave propagates along the north direction, applying the right-hand rule indicates that the magnetic field vector points towards the west direction.

Explanation of Magnetic Field Vector Towards West

The reason the magnetic field vector points towards the west can be understood by considering the relationship between the electric and magnetic fields in an electromagnetic wave. As the electric field vector oscillates upwards, it induces a magnetic field perpendicular to it. This induced magnetic field forms concentric circles around the electric field vector.

Since the electric field vector is pointing upwards, the induced magnetic field will form circles that are oriented clockwise when viewed from above. According to the right-hand rule, the direction of the magnetic field vector is given by the direction of the curling fingers, which in this case is towards the west.

Conclusion

In summary, when an electromagnetic wave propagates along the north direction with its electric field vector pointing upwards, the magnetic field vector will point towards the west. This can be determined by applying the right-hand rule, which establishes the relationship between the direction of propagation, electric field vector, and magnetic field vector in an electromagnetic wave.