Which of the following pairs have same size?

Options

A. `Zn^(2+),Hf^(4+)`
B. `Fe^(2+),Ni^(2+)`
C. `Zr^(4+),Ti^(4+)`
D. `Zr^(4+),Hf^(4+)`

Explanation

`Zr^(4+)` and Hf1 have same size due to lanthanoid contraction.