What is the primary reason the gravitational force inside a uniform spherical shell is zero?
Inside a uniform spherical shell, the gravitational forces from all mass elements cancel out due to symmetry, resulting in a net force of zero at any internal point. As per NCERT, applying relevant law/formula with correct units and sign convention leads to Forces cancel due to symmetry. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.
Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.