$-$ Which statement is CORRECT about cross$-$validation in machinelearning?

A$.$ nk$-$fold cross validation, each data point is contained in k folds.

$8.$ In k$-$fold cross validation, all k Iterations use the same one fold as the testing set.

C$.5-$fold cross validation is less likely to lead to overfitting than $20-$fold cross validation.

D$.5-$fold eross validation always provides a better fit than $10$ fold cross validation.