Question

ionization energy is...
the energy required to add an electron to a specific atom
how much energy it takes to remove an electron from an atom
the energy required to shield the outer electrons from the nucleus
a measure of the ability of an atom to attract electrons

Explanation:

Ionization energy is defined as the energy required to remove an electron from an atom. This is a fundamental concept in chemistry related to atomic structure and electron behavior.

Answer:

"how much energy it takes to remove an electron from an atom"