Correct Answer - A::B::C
a. For a proper explanation , the earth Moon system will be regared as an isolated system. At a particular point in space, the gravitational force of attraction of the earth on astronaut will be balanced by the gravitational force of attraction of the Moon.
b. `V=-GM//r` . As `R` decreases, `GM//R` increases or `-GMM//R` decreases.
c. In case of the sphereical shell, plot of `I` versus `r` is dicontinous.