If `tan 22\frac{1}{2}^\circ = \sqrt{2}-1`, then the value of `cot 67\frac{1}{2}^\circ` is -
(a) `\sqrt{2}+1`, (b) `\sqrt{2}-1`, (c) `\sqrt{3}-1`, (d) `\frac{\sqrt{3}-1}{\sqrt{2}+1}`