Explanation

The correct answer is B because:

• Option A is incorrect: While spot rates are used in the calibration process, the binomial tree itself spreads around the forward rate curve.

• Option B is correct: A properly calibrated binomial interest rate tree spreads out around the implied forward rate curve. The forward rates represent the expected future short-term rates, and the binomial tree models the possible paths these rates could take over time.

• Option C is incorrect: The benchmark rate curve refers to the current yield curve, but the tree spreads around the forward rates derived from this curve.

Key Concept: Binomial trees model the evolution of short-term rates around the implied forward rate curve, with volatility determining the spread.