An ellipse is drawn by taking a diameter of the circle (x−1)2+y2=1 as its semi-minor axis and diameter of the circle x2+(y−2)2=4 is semi-major axis. If the centre of the ellipse is at the origin and its axes are the coordinate axes, then the equation of the ellipse is
a. 4x2+y2=4
b. x2+4y2=8
c. 4x2+y2=8
d. x2+4y2=16