Final answer:
The systems variable in a cooking oven's regulatory system is the air temperature in the oven, which is controlled by the thermostat to ensure proper cooking conditions.
Step-by-step explanation:
The systems variable in a regulatory system such as a cooking oven that would be most relevant is the air temperature in the oven. The thermostat is responsible for regulating the temperature inside the oven to maintain a desired level. It senses the current temperature and adjusts the heating elements accordingly to maintain the set temperature.This is because the main function of an oven is to maintain a certain air temperature to cook food properly. The thermostat within the oven regulates this temperature, making adjustments to the heat input to achieve the desired cooking temperature.
In the context of thermodynamics, the systems variable refers to a characteristic that is being controlled or regulated within a system. The air temperature is a key variable as it directly affects the cooking process and the outcome of the food.