Answer:
The correct option is: D. nitrogen
Step-by-step explanation:
Electronegativity is the capability of a chemical element to attract or pull the bond pair involved in the formation of a covalent bond towards itself.
As the atomic radius of an element increases, its tendency to attract the bond pair towards itself decreases. Therefore, the electronegativity decreases.
Since in the periodic table, the atomic radius increases down a group and generally decreases across a period. So, the electronegativity decreases down the group and generally increases across a period.
Therefore, Nitrogen which belongs to period 2 and group 15 of the periodic table, has the smallest atomic radius among the given chemical elements and thus is the most electronegative element (3.04 on the Pauling scale) among the given chemical elements.