Answer:
The correct answer is Ionization.
Step-by-step explanation:
Ionization energy can be defined as minimum amount of energy that is required to remove an electron from the outer orbital or the valence orbital of an atom.
Ionization energy depends on the size of the atom.If the atom is small in size that means the electrons of outer orbital are strongly attracted by the positively charged nucleus.As a result more energy is required to remove an electron from the outermost orbital of that atom.
As a result the ionization energy of that atom will be high.