The correct answer is Sound waves.

• Echolocation is a technique used by bats, dolphins, and other animals to determine the location of objects using reflected sound. 
• Echolocation pulses consist of short bursts of sounds.

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• ​Bats use echolocation for navigation (flying around at night), for prey detection, and for prey approaching and catching.
  • SONAR, (sound navigation ranging), is a technique used for detecting and determining the distance and direction of underwater objects by using sound waves.
• A wave is defined as a disturbance or variation that transfers energy progressively from point to point in a medium.
  • Electromagnetic waves are formed when an electric field comes in contact with a magnetic field.
  • They are deflected neither by the electric field nor by the magnetic field.
  • Electromagnetic waves do not need any object medium for propagation and can easily travel through the vacuum.
    • Microwaves and radio waves are types of electromagnetic waves.
    • Microwaves are electromagnetic waves with frequencies between 300MHz (0.3GHz) and 300GHz.
    • Radio waves are electromagnetic waves within the frequencies 30KHz - 300GHz and include microwaves.
  • ​Sound waves are longitudinal waves that travel through a medium like air or water.