In order to shift a body of mass m from a circular orbit of radius 3r to a higher orbit radius 5r around the Earth, the work done is:
a) -²ᴳᴹᵐ⁄₁₅ᵣ
b) -³ᴳᴹᵐ⁄₁₅ᵣ
c) -²ᴳᴹᵐ⁄₉ᵣ
d) -³ᴳᴹᵐ⁄₉ᵣ