The weight of a body on the surface of the earth is \( 100 \, \text{N} \). The gravitational force on it when taken at a height, from the surface of earth, equal to one-fourth the radius of the earth is:
\( 25 \, \text{N} \)
\( 100 \, \text{N} \)
\( 50 \, \text{N} \)
\( 64 \, \text{N} \)