1. I believe the answer is: C. running
An activity tend to has a high impact of joint if it includes a certain level of collision between the join and hard surfaces for a long period of time. When we run, the impact happened between the joints in our knees and ankles with the grown everytime we took as step.
2. I believe the answer is: D. athletic issues
Special needs issues refers to the problem that created due to a certain defect in our genetic composition or any form of maltreatment. Athletic issues tend to happen only because we are injured or by using a wrong posture to make athletic movements.