Answer:
gamma rays only is the correct answer.
Step-by-step explanation:
Every radiation has different penetrating power to penetrate in materials and the flow of particles through a material is called penetration power.
Penetrating power of the gamma rays is very high because it has no mass and charges that the reason it can travel far in the air than beta particles and alpha particles.
Alpha particles can be blocked by paper and beta particles can easily passes through paper but it cannot pass through aluminum sheet whereas gamma particles are hardest to blocked, gamma particles can be blocked by heavy shielding.
Thus the radiation can pass through sheet of metak and hit the target is only gamma rays.