ANS:C - beat

• Period Time: The period time refers to the time taken for one complete cycle of vibration or oscillation to occur.
• Oscillation: Oscillation refers to the repetitive movement or variation about a central value. One half of this movement constitutes one oscillation.
• Beat: A beat is the periodic variation in the intensity or amplitude of sound caused by the interference of sound waves of slightly different frequencies.
• Amplitude: The amplitude refers to the maximum displacement or distance moved by a point on a vibrating body from its central position during one complete oscillation.