Electric motors waste energy mainly as heat and sound due to inefficiencies.

Steps:

• Electric motors convert electrical energy to kinetic energy with 90% efficiency, so 10% is wasted.
• The primary waste is thermal energy from electrical resistance and friction in components.
• Sound energy is produced as vibrations and noise during operation.
• Chemical energy is not typically wasted in motors, as they don't involve chemical reactions.

Why D is correct:

• By the law of conservation of energy, inefficiencies in motors generate thermal energy (Joule heating) and sound energy (mechanical vibrations), matching the 10% loss.

Why the others are wrong:

• A: Omits thermal energy, the dominant waste form from resistance.
• B: Ignores sound energy generated by moving parts.
• C: Chemical energy isn't produced; motors use electrical, not chemical, conversion.

Final answer: D