Fact 1: If a thermal conductor is exposed to a source of heat then that conductor may become hot.

Fact 2: Radiant heat is the way the sun heats the planet.

Given the two facts above, answer the question "What can cause a thermal conductor to become hot?" with the following options: 
- exposure to ice
 - exposure to a freezer
 - Evaporation
 - exposure to the sun
 - exposure to metal
 - electricity
 - flow of electrons
 - Electrical energy


 

    exposure to the sun     