Explanation

The Vasicek model is a popular one-factor interest rate model that has the following key characteristics:

1. Mean Reversion: The Vasicek model explicitly incorporates mean reversion through the parameter θ (theta), which represents the long-term mean level that interest rates tend to revert to.

2. Risk Premium: The model includes a risk premium as part of the drift term. The drift in the Vasicek model is given by: $dr_t = κ(θ - r_t)dt + σdW_t$ where κ is the speed of mean reversion, θ is the long-term mean, and the term κ(θ - r_t) represents the drift that includes both mean reversion and the risk premium component.

3. Key Features:

   • The model assumes that interest rates follow an Ornstein-Uhlenbeck process
   • It allows for negative interest rates (unlike the Cox-Ingersoll-Ross model)
   • The risk premium is embedded in the drift term through the parameter θ

Option A is incorrect because the Vasicek model does not have a drift of zero - it has a mean-reverting drift.

Option C is incorrect because the Vasicek model can incorporate a risk premium through the drift term.

Option D is incorrect because the Vasicek model explicitly incorporates mean reversion.

Therefore, Option B is the correct statement as it accurately describes that the Vasicek model incorporates mean reversion and models the risk premium as a component of the drift.