KE of rocket (using derivation of you can get from setting mv^2/r = GMm/r^2, reply to this if you're not familiar with it):
GMm/2r = E_k = 1.67x10^9
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Work Done to get rocket into orbital distance = mass of rocket X change in gravitational potential of rocket
gravitational potential = -GM/r
potentials are at Earth's surface (6400km away from centre of the Earth) and 18000km away from centre of the Earth
= 150 * ((Gx6x10^24)/(6400x10^3) - (Gx6x10^24)/(18000x10^3))
= (150 x G x 6x10^24)(1/6400x10^3 - 1/18000x10^3)
= 6.05x10^9
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Minimum total Work Done = E_k + (work done to get into orbit)
= 6.05x10^9 + 1.67x10^9 = 7.7x10^9 (B)