Which of the following best defines risk?

Risk is best defined as a deviation from the expected result, which encompasses the potential for both positive and negative outcomes based on uncertainty. This definition takes into account that any decision or action may lead to varied results, thus reflecting the inherent unpredictability involved in many situations.

Understanding risk in this context is vital for a municipal arborist, as it relates to assessing potential hazards associated with trees, such as the likelihood of failure, safety implications for people and property, and the environmental impacts of managing tree populations.

The other options do not capture the essence of risk accurately. For instance, a guaranteed outcome suggests certainty and eliminates the possibility of variance, which is contrary to the concept of risk. Positive consequences alone do not adequately represent the potential negative implications of a decision, and a statistical average of outcomes leans more towards a quantitative representation rather than capturing the qualitative aspect of uncertainty involved in risk. Hence, the correct definition of risk encapsulates the variability of potential outcomes, underscoring the unpredictability that comes with decision-making in arboriculture and other fields.