question_answer

If \[f(x)=\cos (\log x)\], then \[f({{x}^{2}})f({{y}^{2}})-\frac{1}{2}\left[ f\,\left( \frac{{{x}^{2}}}{2} \right)+f\left( \frac{{{x}^{2}}}{{{y}^{2}}} \right) \right]\] has the value                                 [MNR 1992]

A)            ?2

B)            ?1

C)            ½

D)            None of these