C and a i’m pretty sure sure!
https://www.pnas.org/content/98/10/5433 (this is where I got it from). Levels of soil nitrogen, phosphorus, calcium and pH, atmospheric CO2, herbivore, pathogen, and predator densities, disturbance regimes, and climate
The component is called 'resting metabolic rate. It operates when the body is at complete rest. It can also be called basal metabolism.