<p>Two statements are given - one labelled as Assertion (A) and the other labelled as Reason (R). Select the correct answer to these questions from the codes (A), (B), (C) and (D) as given below.</p>

<p>Assertion (A) : Separation of Zr and Hf is difficult.<br />
Reason (R) : Zr and Hf have similar radii due to lanthanoid contraction.</p>