Running Vs. Walking Running Is One of the Best Ways to Get Exercise

Running vs. Walking
Running is one of the best ways to get exercise. You do not need to join a gym or buy expensive equipment to go for a run. But you might be surprised to learn that walking can be just as good for you as running. In fact, going for a walk might be even better for you than going for a run.
Running can help lower your blood pressure and reduce your risk for heart disease. However, recent research by the American Heart Association shows that walking is just as good for your heart as running. A brisk walk can lower the risk for heart disease, high blood pressure, and high cholesterol just as much as running does. The only catch? You have to walk twice as long as you would run. In order to get the benefits of a 15-minute run, you need to walk for 30 minutes.
Walking is just as good as running when it comes to cardiac health, but there are other ways in which walking can actually be better for you than running. Running can be tough on your body, especially your joints. In fact, a recent study published by the American College of Sports Medicine shows that as many as 40 to 50 percent of runners suffer a running-related injury every year.
Walking does have some advantages over running. However, one thing is for sure: either one is better for you than sitting on a couch!
Question: What is the author's main purpose in writing this passage?

A) To inform the reader about the disadvantages of certain exercise routines.
B) To persuade readers to exercise by running rather than walking.
C) To describe the advantages and disadvantages of running and walking.
D) To entertain the reader with a personal story about exercising.