Question

Isaac wants to make s'mores. He holds a marshmallow on a metal skewer over a fire. A few seconds later, the marshmallow is cooked and the skewer feels warm. What most likely happened?

The fire heated the surrounding air, which cooked the marshmallow.
The heat generated from the marshmallow flowed in the form of thermal energy to the skewer and fire.
The heat from the skewer cooked the marshmallow.
Thermal energy in the form of heat moved from the fire to the skewer and marshmallow.

Answer 1

Thermal energy in the form of heat moved from the fire to the skewer and marshmallow.

Heat always flows from hotter to cooler objects (by radiation, convection, and conduction). The fire heated the marshmallow and the skewer; the skewer then conducted heat along its length so it felt warm.