circulatory, excretory, and respiratory circulatory, endocrine, and reproductive skeletal, muscular, and nervous skeletal, digestive, and respiratory
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which human body systems work directly together to allow locomotion?
Possibilities:
- circulatory, excretory, and respiratory
- circulatory, endocrine, and reproductive
- skeletal, muscular, and nervous
- skeletal, digestive, and respiratory

skeletal, muscular, and nervous