Which of the following is an example of a definable risk?

A definable risk is one that can be clearly identified and quantified, making it suitable for insurance purposes. The option of a diamond necklace fits this definition well, as it is a tangible asset with a specific value that can be insured. In contrast to the other choices, a diamond necklace has concrete characteristics that insurance companies can assess for risk, including its market value, susceptibility to theft, and potential for damage.

The other choices do not represent definable risks as clearly. A family photograph, for instance, while it can have sentimental value, lacks a defined market value and the quantifiable characteristics required for insurability. A riverbed might involve risks related to erosion or flooding, but it is a natural feature that is not easily quantifiable in an insurance context. An abstract concept, by its nature, cannot be insured because it lacks physical attributes and a measurable risk profile.

Thus, the diamond necklace stands out as a well-defined risk due to its clear, assessable value and the specific risks associated with its ownership and care, aligning perfectly with the definition of a definable risk.