Suppose for a given portfolio that key rate changes are considered to be changes in the yield on 1-year, 5-year, and 10-year securities. Estimated key rate durations are KeyDur₁ = 0.50, KeyDur₂ = 0.70, and KeyDur₃ = 0.90. What is the percentage change in the value of the portfolio if a parallel shift in the yield curve results in all yields declining by 50 bps?

A. ‒1.05%.

B. +1.05%.

C. +2.10%.