Final answer:
When the thermostat calls for heat, gas flows to the ignition module, and a voltage is applied to create a spark for ignition. Answer A is correct.
Step-by-step explanation:
When the thermostat (T'stat) calls for heat, gas flows to the ignition module, and a voltage is applied to the electrode to produce a spark which then ignites the flame. Therefore, the correct answer is A. Ignition module, voltage.
The ignition process can be characterized as a thermal action where the fuel-air mixture ignites, causing a significant temperature increase within the cylinder of a gasoline-burning internal combustion engine.
According to the ideal gas law, which states PV = NkBT, this rapid temperature rise results in a pressure spike, since the cylinder volume does not have time to change immediately. The subsequent increase in pressure drives the piston, performing work and thus converting the chemical energy in the fuel into mechanical work.