The conjugate axis of a hyperbola with centre at the origin and transverse axis along the y-axis is 14 units long, and its eccentricity is 25. Which of the following is the equation of this hyperbola?
a) 196x2−49y2=1
b) 49y2−196x2=1
c) 196y2−196x2=1
d) 196y2−49x2=1