Answer:
alpha
Step-by-step explanation:
As unstable nuclei breaks into some other nuclei in order to attain stability. We will have three type of nuclei decay as following
1). Alpha Decay = it is positively charged high speed helium nuclei which will have energy in form of kinetic energy. Since these are heavy nuclei so penetration power of them is small and they are positively charged
2) Beta Decay = In this type of decay we will have negatively charged electrons released by the unstable nuclei and they move with high energy as they are of lesser mass. Penetration power of beta is more than alpha
3) Gamma Decay = It is neutral and massless photons which contains high energy. Penetration power of gamma is highest among all.
So here as we know that radiation particle is deflected towards negative terminal so it must be a positive particle so here correct answer must be
alpha