Answer: The correct answer is solar cell.
When energy is changed from one form to another, some of the energy is lost to the surroundings as waste thermal energy.
From the given options,
Electric drill: Electric drill converts the electrical energy into mechanical energy. When the drill break the the object then the mechanical energy is converted into the heat energy.
Car engine: Car engine converts the chemical energy into the thermal energy. This thermal energy gets converted into the mechanical energy. Then, this mechanical energy is used to accelerate the vehicle.
Hydroelectric dam: Here, the potential energy stored in the water at some height is converted into mechanical energy. Then, this mechanical energy is converted into the kinetic energy. Then, finally, this kinetic energy is converted into electrical energy.
In above options, there is a dissipation of energy while one form of energy gets converted into another.
The more steps needed to arrive at the desired energy or the more types of energy that are generated, the more energy is wasted.
Solar cell: The solar cell converts the solar energy into electrical energy.
Therefore, a solar cell have the least amount of wasted energy.