Which of the following is the correct expression for gravitational acceleration (g) at a height h, given go refers to gravitational acceleration on the earth’s surface and Ro refers to effective radius of earth?

• A. g=go[Ro/(Ro+h)]2
• B. g=go[Ro/(Ro-h)]2
• C. g=go[(Ro+h)/2Ro]2
• D. g=go[(Ro-h)/2Ro]2