Answer : Option C) Fluorine and Chlorine.
Explanation : According to the given options; the two elements that have similar characteristics are Fluorine and Chlorine.
As both the elements belong to the same group in the periodic table which is the halogen group and they have the same valency although their reactivities differ. Fluorine is more reactive than chlorine if compared. They both are placed in the same group which is Group 7 in the modern periodic table. As both the elements have 7 electrons in their outermost shell.