Concept:Amplitude is the maximum displacement of an object from its equilibrium position in simple harmonic motion.Explanation:In simple harmonic motion, an object moves back and forth about a fixed equilibrium position.The greatest distance it reaches on either side of this position is called the amplitude.Amplitude is a positive scalar quantity, usually denoted by A.It measures the size of the oscillation and remains constant for an ideal system.Thus, the maximum displacement on either side of the equilibrium position is the amplitude.Answer:B. amplitude