Answer:Of the following sentences which come closest to stating the main ideas in this paragraph are:
That makes walking a simple activity for those new to exercise.
Walking is less likely than other exercises to cause injury to leg tendons and muscles.
The paragraph inserts the points about the benefits of walking and being the simple exercise.
It emphasizes walking being the simplest activity and harmless. Further, through its main points, it inserts that the people new to exercise can adapt to it easily without causing any kind of injury to themselves.
im new :)