Answer:
The correct answer option is d. energy but not matter.
Explanation:
A system which only allows the exchange of energy to its surroundings and not the matter is known as a closed system.
An example of a closed system is when you place a lid on a saucepan. The lid does not allow the matter to enter in or leave the saucepan but it does allow the energy to transfer in the form of heat.
Therefore, energy but not matter can enter and exit a closed system.
