Answer: underlying is a futures price.

## Explanation The key difference between the Black model and the standard market model is: **Black model**: Assumes the underlying is a forward price **Standard market model**: Assumes the underlying is a futures price This distinction is important because: - Forward prices and futures prices differ due to the daily settlement feature of futures - The Black model is more commonly used for interest rate options where the underlying is typically a forward rate - The standard market model is more appropriate for options on futures contracts Therefore, option A is correct: the standard market model assumes the underlying is a futures price.

Author: LeetQuiz Editorial Team