Explanation:

• A (Key rate duration) is correct because it measures a bond's sensitivity to changes in the benchmark yield curve at specific maturity segments. Unlike effective duration, key rate duration helps identify 'shaping risk,' which refers to a bond's sensitivity to changes in the shape of the yield curve (e.g., flattening or steepening).

• B (Effective duration) is incorrect because it assumes a parallel shift in the yield curve, meaning all yields change by the same amount. It does not account for changes in the shape of the yield curve.

• C (Macaulay duration) is incorrect because it measures the sensitivity of a bond's full price to changes in its own yield to maturity, not to changes in the benchmark yield curve's shape.