The correct option is B 3.278km s−1.
The orbital velocity in a circular orbit close to the earth is v=√gR.
The velocity required to escape ve=√2gR.
Hence additional velocity required is ve−v=(√2−1)√gR.
Therefore,
ve−v=0.414×√9.8×6400×103
=3278.71m/s =3.278km s−1.