A satellite is moving around the sun in an elliptical orbit. 'm' is the mass of the sun and 'a' is the semi-major axis of the elliptical orbit. The velocity of the satellite when it reaches at 'a' is:

a) √(Gm/a)
b) √(a/Gm)
c) √(Gm/(2a))
d) √((2a)/Gm)