The charging system maintains the _____'s state of charging. A: symbiotic B: prehistoric C: metabolism D: battery

The passage is chiefly concerned with A: offering an explanation of the process that causes a phenomenon, and a counter-explanation B: demonstrating how two processes act in symbiotic coordination in causing a phenomenon C: establishing how one process causes a phenomenon which is resisted by a second process D: explaining two separate processes which cause a mostly identical phenomenon E: outlining the essential differences between two distinct phenomenon that issue from a single cause