The curve xy=c is rectangular hyperbola, where c is constant. Figure shows the curves drawn for c=0.1 and c=0.3.
It can be seen that circle x2 +y2 = 1 intersects the curve xy=c at two points, coordinates of point of contact depend upon c.
Hence the distance between point of contacts depends upon c.
But in list of options of answers, all the numbers are not related to constant c.
Hence answer of this question :- 4) None of these