The correct option is A Atomic radius and electron gain enthalpy (negative value)
(a) As we move across the period, atomic radius decreases, the negative value of electron gain enthalpy increases.
(b) Ionization energy and nuclear charge increases across the period from left to right.
(c) Ionization enthalpy and electron gain enthalpy (negative value) increases across the period from left to right.
Thus, Atomic radius and electron gain enthalpy (negative value) show reverse properties on moving along a period from left to right .