The threat of an unsafe environment
If you have good cardio respiratory endurance, then you'll be able to do rigorous physical activity for longer amounts of time, because like other muscles in your body, the more you stretch them the stronger they get and the longer they would last.
Hope that helps and makes sense :)
I believe the answer to your question is external stimuli
Answer:next bc you got it correct I believ
Explanation:
STDs are infections spread from person to person during sexual contact.
