Answer: (C) energy
Earth is an open system with respect to energy because the earth receives energy from the sun in the form of solar energy. This energy is absorbed by the oceans and terrestrial land. The solar energy in the form of thermal energy heat up the oceans and the terrestrial land which results in the release of thermal energy by the oceans and terrestrial lands. Some of this thermal energy is reflected back to the exterior of the earth which supports the fact that earth is an open system.