Which element would most likely have an electron affinity measuring closest to zero? na al rb ar

The answer is:

Ar

The explanation:

when:

-electron affinity goes through the periodic table from left to right and from down to up  as shown in the attached pic.

and:

when The Electron affinity is  the change in energy  of a neutral atom (in its gaseous phase) when a negative ion forms when an electron is added . In other words, the neutral atom's like of gaining an electron.

-electron affinity is the ability of an atom to accept an electron.

-Unlike electronegativity, electron affinity is a quantitative measurement of the energy change that happens when an electron is added to a neutral gas atom.

-The more negative the electron affinity value, the higher an atom's affinity for electrons.

so, according to that and according to the attached pic so, the answer is Ar