Sonar system is found in
A) Otter
B) Bat
C) Whale
D) Both B and C

Hint:It is a system of navigation found in underwater animals or specially marine organisms. It helps in detecting objects through echolocation.

Complete answer:
Let’s discuss the options and find the correct answer.
Sonar system is also called the Sonar navigation ranging system that is usually a marine water navigation. It is very helpful in detecting objects or for identifying each other under the surface water. In case of otters, sensors or customers such as seabed or natural mappings are carried by them such as CTD ADCP etc. Here many beamed sonar systems can easily be integrated.
In case of bats, the Sonar system is effective in emitting sounds which bounce the objects and an echo comes back again. It is helpful as they respond to echo and in this way they can understand the danger and pray are captured in this way.
In the case of whales and dolphins, the sonar system that is found is the bisonar system of navigation. For searching the predators and to find the prey, dolphins or whales use echolocation methods and as a result the animals become confused and the process of mating and feeding continues. The sounds made by them are very sophisticated and reflect back very early.

Hence Option D: Both B and C is the correct answer.

Note:Not all time sonar systems give positive results. Use of sound navigation or sonar sometimes leads to injury and sometimes even death. So, there are also advantages and disadvantages of it.