Answer:
Beta rays
Step-by-step explanation:
as we know that as per energy we can say that maximum energy is for gamma rays and minimum energy is for alpha rays
so here alpha rays are of least energy and it can not penetrate through the paper
while gamma rays are of maximum energy which is due to transitions in nuclear level so it can penetrate through any thickness
So here we have to choose which can penetrate through paper but can not penetrate through wood
so it is of moderate energy
So this must be Beta rays