Lanthanoid contraction is caused due to:

Options

A. The appreciable on outer electrons by `4f` electrons from the nulcear charge
B. The appreciable on outer electrons by `5f` electrons from the nulcear charge
C. the same effective nuclear charge from `Ce` to` Lu`
D. The imperfect shielding on outer electrons by `4f` electrons from the nulcear charge.

Answer

4

Explanation

Lanthanide contraction is due to ineffective shielding produced by larger `f`-subshell.