From left to right in a period of elements, ionization energies tend:
a) remain constant
b) increase
c) decrease
d) alternate

The correct option is B

Explanation:

Ionization energy is the minimum amount of energy required to remove a valence electron from an atom in its gaseous state. The fewer the electrons on the outermost shell, the lower the ionization energy; this is because the fewer the electrons on the outermost shell, the lesser the energy required to remove this valence electrons. Hence, ionization energy increases from left to right across the period.