Question

multiple-choice question
what is atomic radius?
the size of the atom
the shape of the atom

Explanation:

Atomic radius is a measure related to the size of an atom, specifically the distance from the nucleus to the outermost electron shell (or a measure of the atom's size). The "shape of the atom" is not what atomic radius describes, as atomic radius pertains to size, not geometric shape.

Answer:

The option "The size of the atom" (the first option with the checkbox)