Fact 1: Alight bulb requires electrical energy to produce light.

Fact 2: Solar-powered lights that use LED bulbs provide the most efficient and most hours of light at night.

Given the two facts above, answer the question "In order to operate at night, solar-powered LED lights require what?" with the following options: 
- sun's heat
 - electrically
 - adding heat
 - focusing a lens
 - hydrogen and oxygen
 - kinetic energy
 - electrical energy
 - direct energy


 

       electrical energy  