# For which value of k does the pair of equations $x^2-y^2$ = 0 and $(xâ€“ k)^2$ + $y^2$ = 1 yield a unique positive solution of x? (a).2 (b).0 (c)$\sqrt{2}$ (d)$-\sqrt{2}$

 [ A ]    a [ B ]    b [ C ]    c [ D ]    d
 Answer : Option A Explanation :