For the single-factor Hull and White model which of the following is false a The term structure is assumed to shift rigidly in a sense b The model would work well for options on interest rate spreads

b. The model would work well for options on interest rate spreads.

The single-factor Hull and White model assumes that the term structure shifts "rigidly" and that the only random factor is the short rate. However, it does not work well for options on interest rate spreads because it does not capture the dynamics of the spread between two different interest rates.