Which of the Following Is Not a Feature of the Exponential

Multiple Choice

Which of the following is not a feature of the exponential splines fitting approach?

A) All its parameters may be estimated simultaneousy using OLS regression.
B) The most popular form is the cubic exponential one.
C) There is an additional parameter $m$ over that of the cubic spline method.
D) The parameter $m$ is the long-maturity limit of the forward rate.