Answer: Option (a) is the correct answer.
Step-by-step explanation:
As the given situation shows that water is being added to water. This will liberate heat into the surround as the reaction will be exothermic in nature.
It is known that chemical reactions in which heat is released are known as exothermic reactions.
Hence, when more water is added to this tank the temperature of the system will increase due to release of heat.
Thus, we can conclude that if more water is added to this tank the temperature of the system will increase.