The correct answer is A. Fluorine.
Electronegativity is the ability of an atom to attract electrons to itself. Fluorine has the highest electronegativity of any element in the periodic table, followed by oxygen, chlorine,
and nitrogen. This means that fluorine is more likely to attract electrons than any of the other elements listed.Sodium is a metal that is located in the first group of the periodic table. It has a low electronegativity, which means that it is not very likely to attract electrons. Chlorine is a non-metal that is located in the seventh group of the periodic table. It has a higher electronegativity than sodium, but it is still not as electronegative as fluorine. Oxygen is a non-metal that is located in the sixth group of the periodic table. It has a higher electronegativity than chlorine, but it is still not as electronegative as fluorine.
In conclusion, the most electronegative element among the following is A. Fluorine.