Proton rays are the rays which can penetrate the most deeply into our body.
Answer: D
Explanation
The radiations are surrounding our atmosphere.
The radiations like alpha rays cannot penetrate dead skin cells while the beta rays can penetrate up to some layers of the skin.
The gamma rays are not a beam of energetic particles like alpha and beta rays, they are beam of energies released in order to stabilize the daughter nuclei.
But the rays which can penetrate more deeply in human body is proton rays and X-rays.
The proton rays are the beam of energetic protons which are positively charged.
They are heavy beam of energies.
The proton rays can penetrate the skin as well as reach the damage cells or tumor cells and they can cure them using proton therapy.