The natural functions of earth seem all in one way or another. interconnected the same separate

The correct answer is - interconnected.

All of the natural function on our planet are interconnected, and they all influence each other in multiple ways. If we take the spheres of the Earth, we can easily notice that the atmosphere influences the hydrosphere by warming or cooling it, as well as acidifying it in certain occasions, the hydrosphere influences gets back to the atmosphere with the water vapor going into it, thus changing its composition and creating clouds. The biosphere uses the air and water to survive, but it also gives back CO2 and oxygen to the atmosphere which makes big portion of its composition, and that influences the temperature that is needed for the survival of the organisms, as well as influencing the amounts of gases and temperature in the water etc.

i think the answer is a, hope this is right, that would be my best guess.