A fish swimming in water possesses mechanical energy.
(A) true
(B) false

Hint: Fish lives in water and the energy is needed to survive and thrive is obtained from the food it eats. They have gills to breathe that is to take in oxygen and to give out the carbon dioxide. They do not have to come out of the water to take in oxygen, they use the dissolved oxygen in the water.

Complete step by step answer:
When the fish moves, no work is being done on the fish by any external system but the definition of mechanical energy states that mechanical energy is the energy stored in moving objects.The energy needed to move is taken from food that is chemical energy of the food is converted to such a suitable form which is stored in the fish body and it utilizes that energy to move. The fish swimming in water is an example of mechanical energy.
Hence the given statement is true, so, the correct option is (A).

Note: Mechanical energy can be summed up as the sum of potential and kinetic energy stored or possessed by the body which is either at rest, either in motion. Mechanical energy is used to do work. Since energy can be converted to different forms, one real life example is an electric generator in which electricity is converted in mechanical energy.