Answer: Option (b) is the correct answer.
Explanation:
Elements of actinide series include Ac, Th, Pa, U, Np, Pu, Am etc and all these elements of actinide series are radioactive in nature.
Alkaline earth metals are the metals of group 2. These include Be, Mg, Ca, Sr, Ba, Ra. Out of these only radium is radioactive in nature.
Halogens are the elements that have completely filled shells. These include He, Ne, Ar, Kr, Xe, Rn.
Non-metals are the elements which are electron deficient. For example, carbon, sulfur, selenium etc are all non-metals.
Thus, we can conclude that actinides is the family in the periodic table that has elements which are all radioactive.
