What is the danger of being within the flammable/explosive range of a substance?

Being within the flammable/explosive range of a substance indicates that the concentration of that substance in the air is such that it can ignite and potentially cause an explosive reaction when exposed to an ignition source. The flammable range consists of the lower and upper limits of concentrations, where, if the air-fuel mixture is within these limits, simply igniting it can lead to fire or explosion. This situation represents a significant hazard, as the presence of an ignition source could lead to rapid combustion and release of energy, resulting in injuries, property damage, or loss of life.

The other choices do not accurately represent the implications of being within the flammable/explosive range. Safe storage conditions would require avoiding such ranges, and being in this range does not prevent combustion or automatically suppress flames; rather, it increases the risk of ignition and fire.