Final answer:
Rayleigh's equation is used to determine the minimum heat release rate for flashover, which is a critical fire development stage.
Step-by-step explanation:
The formula used to determine the minimum heat release rate that leads to flashover is A) Rayleigh's equation. Flashover is a fire development stage where all exposed surfaces in a compartment reach ignition almost simultaneously, making the entire room combustible. In most flashover scenarios, the heat release rate is critical and Rayleigh's equation takes into account factors such as the geometry of the compartment, ventilation, and fuel properties to estimate this critical heat release rate.