For each of the following prediction tasks, state whether it is best thought of as a classification problem or a regression problem. (a) Based on sensors in a person's cell phone, predict whether they are walking, sitting, or running. (b) Based on sensors in a moving car, predict the speed of the car directly in front. (c) Based on a student's high-school SAT score, predict their GPA during freshman year of college. (d) Based on a student's high-school SAT score, predict whether or not they will complete college