It’s #2 hope this helps !
It strengthens your bones to be able to handle large amounts of pressure and weight on your body. I know this isn't related, but when a person breaks their ankle or something else they tend to heal quicker because they're athletes. So one way or another, increasing strength, helps to increase your capacity for exercising.
Interacting with Other Systems. The digestive system works very closely with the circulatory system to get the absorbed nutrients distributed through your body. The circulatory system also carries chemical signals from your endocrine system that control the speed of digestion.
Experiences
Hope this helps! :)