Electronegativity generally decreases as atomic radius increases and increases with the number of valence electrons, especially as the elements approach the right side of the periodic table.
Based on the provided options, the element with the lowest electronegativity would be:
an element with a small number of valence electrons and a large atomic radius.
This is because a large atomic radius implies that the valence electrons are farther from the nucleus, reducing the element's ability to attract electrons. Having a small number of valence electrons also contributes to lower electronegativity.