A. as hard as possible so that it adds more stability to your foot.
B. hilly so that you can improve your cardiovascular endurance.
C. smooth and soft so that it can cushion the stresses of running.
D. uneven so that the tendons and ligaments in the ankles and knees are strengthened.
The best surface for a beginner to run on is smooth and soft so that it can cushion the stresses of running. For a more advanced runner, hills could be beneficial in improving their training and cardiovascular endurance.
