What types of radiation are present in the magnetic field

Answer: Option B

To solve this question, you need to apply your FLHR. From the image, you will be able to know the orientation of the force F (thumb) and the magnetic field M (first finger).

For the radiation path that goes straight, it indicates that it is not affected by the magnetic field. That means the radiation has no charge, hence it is gamma rays (a type of electromagnetic wave)

For the radiation path that curves upwards, that means there is a force acting to the top of the image. So orientate the FLHR according and the 2nd finger (convention current) points to the right.

Note the the direction of the convention current is the path in which a positive charge will take, so the radiation must be positive charge, i.e helium nucleus (alpha particles).