Here's a problem to solve: Anita sprinted around the track at her school. At the end of her run, she was taking more air into her lungs and her heart rate had increased. What systems regulate Anita's breathing rate and heart rate?

Among the 4 following options, which is the correct answer?

- A: muscular and skeletal
 
- B: nervous and endocrine
 
- C: digestive and excretory
 
- D: respiratory and circulatory
 