The orbital velocity of a satellite at a height h from the surface of a planet having mass M and radius R is given by, v=√GM(R+h)=√gR2(R+h) Given, R=6.4×106 m,
h=2.5×104 m
Since, h<<R,
⇒v=√gR
⇒v=√10×6.4×106
⇒v=8×103 m/s
⇒v=8×1031000 km/s
⇒v=8 km/s
Hence, option (d) is correct answer.