What ensures that a planet moves faster at perihelion than at aphelion?
Angular momentum conservation (mrv = constant) implies that at perihelion (smaller r), the speed v is greater than at aphelion (larger r), as derived from Kepler’s second law. As per NCERT, applying relevant law/formula with correct units and sign convention leads to Conservation of angular momentum. 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.