Explanation:

Key rate duration measures the sensitivity of a bond's price to changes in specific key rates along the yield curve, while effective duration measures the sensitivity of a bond's price to parallel shifts in the entire yield curve.

When there is a parallel shift in the benchmark yield curve (meaning all rates move by the same amount), key rate durations sum to give the same interest rate sensitivity as effective duration. This is because:

1. Key rate duration decomposes interest rate risk into exposures to specific points on the yield curve
2. Effective duration measures overall price sensitivity to parallel yield curve shifts
3. For parallel shifts, the sum of key rate durations equals the effective duration

Why not the other options:

• Modified duration assumes a flat yield curve and measures sensitivity to yield-to-maturity changes, but doesn't account for non-parallel shifts or embedded options
• Macaulay duration is a weighted average time to receive cash flows, not a direct measure of price sensitivity to interest rate changes

Therefore, for parallel shifts in the benchmark yield curve, key rate durations indicate the same interest rate sensitivity as effective duration.