Answer:
sulfur
Step-by-step explanation:
From the given lists of elements, the one with the most electronegativity is Sulfur.
Electronegativity is of an element is a property that combines the ability of its atom to lose and gain electrons.
It is a measure of the relative tendency with which the atoms of the element attract valence electrons in a chemical bond.
Using the Pauling's electronegative table of elements;
Here are electronegativity values of the given elements;
selenium 2.4
arsenic 2.0
phosphorus 2.1
sulfur 2.5
We see that the value of sulfur is the highest.