A spacecraft of negligible mass compared to Earth is to be transferred from a circular low-Earth orbit of radius 7.0×106m to a geostationary orbit of radius 4.2×107m. Using GM⊕=3.99×1014m3s−2, the additional mechanical energy required per kilogram of the spacecraft is closest to
(a) 4.8×107Jkg−1
(b) 1.2×107Jkg−1
(c) 2.4×107Jkg−1
(d) −2.4×107Jkg−1