Ionic radii vary in :

1.  Inverse proportion to the effective nuclear charge.

2.  Inverse proportion to the square of effective nuclear charge.

3.  Direct proportion to the screening effect.

4.  Direct proportion to the square of screening effect.

HINT: Ionic radius decreases as the effective nuclear charge increases.

Explanation:
Radius of the ion depends on the effective nuclear charge, more the charge, more heavily the electrons are attracted towards the center and lesser in the size.

Ionic radius decreases as the effective nuclear charge increases.

Ionic radius ∝ 1/effective nuclear charge

Screening effect - Screening effect is also known as the shielding effect. This phenomenon occurs when the nucleus reduces its force of attraction on the valence electrons due to the presence of electrons in the inner-shell.

Further, ionic radius increases as the screening effect increases.

Ionic radius ∝ screening effect

Hence, option 1 and 3 are correct answers.