True. Among the four categories of fire phenomena mentioned, premixed flames are indeed the predominant category. Premixed flames occur when a mixture of fuel and oxidizer (such as air) is combined in the right proportion before ignition. This mixture is then ignited, and the combustion occurs as a flame front propagates through the pre-mixed gas. Most common fires, like those in everyday combustion engines or gas stoves, are examples of premixed flames. Diffusion flames, smoldering, and spontaneous combustion are less common in comparison. Hope this helps