Answer: Focuses exclusively on downside risk.

**Explanation:** - **Option A** is correct because Roy's safety-first criterion evaluates only downside risk, unlike mean-variance analysis, which considers risk symmetrically (both above and below the mean). Safety-first rules are designed to minimize the probability that a portfolio's return falls below a specified threshold level (RL). - **Option B** is incorrect because the safety-first ratio uses standard deviation, not semideviation, as the risk measure. While semideviation and related metrics focus on downside risk, they are not part of Roy's safety-first criterion. - **Option C** is incorrect because Roy's safety-first criterion assumes that portfolio returns, not asset prices, are normally distributed. The normal distribution is more suitable for modeling returns than asset prices, as asset prices cannot be negative, whereas returns can theoretically be unbounded.

Author: LeetQuiz Editorial Team