Assume you have a training dataset consisting of N observations and D features. You use the closed$-$form solution to fit a multiple linear regression model using ridge regression. To choose the penalty strength A$,$ you run leave$-$one$-$out $($LOO$)$ cross validation searching over L values of A$.$ Let Cost$($N$,$ D$)$ be the computational cost of running ridge regression with N data points and D features. Assume the prediction cost is negligible compared to the computational cost of training the model. Which of the following represents the computational cost of your LOO cross validation procedure?

A$.$ LN Cost$($N$,$ D$)$

B$.$ LN Cost$($N$-1,$ D$)$

C$.$ LD$-$Cost$($N$-1,$ D$)$

D$.$ LD Cost$($N$,$ D$)$

E$.$ L Cost$($N$-1.$ D$)$

F$.$ L$-$ Cost$($N$,$ D$)$