Final answer:
Natural systems, like the soil in a floodplain, are open systems in terms of both energy and matter, allowing for a continuous exchange with the environment, which differs from closed systems that are isolated from their surroundings.
Step-by-step explanation:
Systems encountered in nature, such as the soil in a floodplain, are both open systems in terms of energy and matter. In open systems, there is a continuous exchange of both matter and free energy with the environment. For instance, a floodplain soil ecosystem will have matter, such as nutrients and water, flowing in and out, and energy from the sun being absorbed by plants.
On the other hand, a closed system is isolated in terms of energy and matter exchange with its surroundings, which is not the case for most natural biological systems. Therefore, the correct answer to whether systems in nature at Earth's surface are open or closed in terms of energy and matter is option D) both A and C - they are open systems in terms of both energy and matter.