Answer: Option (A) is the correct answer.
Step-by-step explanation:
When Sam placed ice in a pot on a stove then there will be transfer of heat from the stove to the pot and then from the pot to the ice.
As a result, solid state of ice changes into liquid state of water because of melting of ice.
Thus, we can conclude that the heat from the stove is the variable that is causing water to change state.