The device which converts mechanical energy into electrical energy is ____________.

Correct option is B

The correct answer is (B) electric dynamo.

A generator converts mechanical energy into electrical energy. It is also known as a dynamo. 

Explanation:

• Generators use electromagnetic induction to convert mechanical energy into electrical energy. 
• The principle of electromagnetic induction states that when a conductor is connected to a changing flux, it will induce an electromotive force (EMF) across it. 
• The value of the induced EMF depends on the rate of change of the flux. 
• Hydroelectric power plants use generators to convert the energy in moving water into electrical energy.

Additional information:

• An electric motor is a device that converts electrical energy into mechanical energy. It works by using a magnetic field to create a force, called torque, that rotates a shaft and produces motion. 
• A dry cell is a type of battery that converts chemical energy into electrical energy. It's a portable electrochemical cell that uses a paste or gel electrolyte instead of a liquid. 
• A compass needle is a small magnet that points north and south, indicating the Earth's magnetic field. It's used in compasses to find direction.