Ionization refers to the process of

Achanging from one period to another.
Cturning lithium into fluorine.
Blosing or gaining protons.
Dlosing or gaining electrons.

Verified Answer :

The ionization
or ionization energy is the process wherein the energy necessary to remove an
electron from the neutral atom. When located in the periodic table, it
increases across the row and decreases going down. The ionization energy is
greatest for the noble gases. For example, the ionization energy for fluorine
is 1681.6 kJ/mol.  It means that it takes
1681.6 kJ/mol of fluorine to completely remove an electron or ionize it. The answer
is d. losing or gaining electrons.

it refers to the process of losing and gaining of electrons