The likelihood of a crash and its resultant injury severity is a combination of which two factors?

• A. Deterministic
• B. Stochastic factors
• C. Deterministic and stochastic factors
• D. Random, unpredictable

Answer: (C)

Crash likelihood and injury severity come from two kinds of influences: deterministic factors are the predictable, systematic elements such as vehicle speed, mass, safety belt use, vehicle safety features, road geometry, and weather. Stochastic factors are the random, chance elements that vary from event to event, like small differences in driver attention, reaction time, timing of a hazard, or the exact angle of impact. Together, these explain why outcomes vary even under similar conditions—you can anticipate risk from the deterministic side, but the exact crash occurrence and injury severity are shaped by random variation. That’s why the best answer includes both deterministic and stochastic factors. Detailing only one type misses part of what drives risk, and calling things random and unpredictable is too vague to capture the structured influences at play.