In which of the following cases forces may not be required? To keep the:

Explanation

The correct answer is Option B: 'The momentum of the particle remains constant.' This indicates no net external force is acting on it, in accordance with Newton's first law and the principle of conservation of momentum. Option A is incorrect because circular motion requires a centripetal force to maintain the path. Option C is incorrect in the context of the question, as it assumes no resistive forces; however, if there are resistive forces present, a force is required to maintain the constant speed. Option D is incorrect because constant acceleration necessitates a continuous net force, as described by Newton's second law.