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 elements with a small number of valence electrons, especially metals, tend to lose electrons easily rather than gaining them, resulting in lower electronegativity. Additionally, a larger atomic radius means the valence electrons are further from the nucleus, reducing the effective nuclear charge felt by those electrons and also leading to lower electronegativity.