The concept of physical hazard is best described as:

The concept of physical hazard pertains specifically to the tangible, measurable aspects of a risk that can influence the likelihood of an insurance loss occurring. This can include factors such as the condition of a building, the presence of safety equipment, or environmental features that could contribute to the risk involved. For instance, an older building may have specific physical hazards such as outdated wiring or structural weaknesses, which could make it more susceptible to fire or collapse.

This definition distinguishes physical hazards from other related concepts. The behavioral characteristics of the insured, mentioned in another option, focus on the actions and decisions of individuals, which are categorized under moral hazards. The potential severity of a loss if it occurs refers to the concept of loss severity, rather than the physical characteristics influencing the risk. Lastly, the range of events that may lead to a loss describes perils, which are different from physical hazards because they focus on the events rather than the characteristics of the objects or situations involved in the risk. Thus, the correct choice captures the essence of physical hazards, emphasizing the intrinsic attributes of the risk itself.