Two physical systems are in thermal equilibrium if there is no net flow of thermal energy between them when they are connected by a path permeable to heat.
Answer:
C- Heat does not flow because both substances are at the same temp.
Explanation:
For example when your holding a warm cup of tea or something and you compare your hand temp. to the tea's temp. it would be known as thermal equilibrium. A point where both objects are at the same temp. or close.
