What helps identify an energy-efficient appliance?

Correct answer: Energy rating

The governing concept is energy efficiency: an appliance is energy-efficient when it performs its intended work while using comparatively less electricity. The energy rating, usually displayed on an official label, helps consumers compare appliances such as fans, refrigerators, or air conditioners. A higher efficiency rating generally indicates lower electricity consumption for similar performance, although the exact scale may differ by product or rating system. Therefore, option C is correct because the energy rating provides relevant information about electricity use. Shoe number, wall height, and cloth colour have no meaningful connection with an appliance’s energy consumption or operating efficiency.