Choose all the valid answers to the description about linear regression and logistic regression from the options below: A. Linear regression is an unsupervised learning problem; logistic regression is a supervised learning problem. B. Linear regression deals with the prediction of continuous values; logistic regression deals with the prediction of class labels. C. We cannot use gradient descent to solve linear regression. Instead, we can only use the closed-form solution to tackle the linear regression problem. D. Linear regression is a convex optimization problem whereas logistic regres- sion is not.