Question

a. the digestive and skeletal systems work together to produce and transport immune cells throughout the body.
b. the skeletal and circulatory systems work together to produce and transport immune cells throughout the body.
c. the circulatory and respiratory systems work together to produce and transport immune cells throughout the body.
d. the muscular and nervous systems work together to produce and transport immune cells throughout the body.

Explanation:

To solve this, we analyze each option:

• Option A: Digestive system (breaks down food) and skeletal system (support/protection) don't produce/transport immune cells. Eliminate A.
• Option B: Skeletal system (bone marrow produces immune cells) and circulatory system (blood transports them) work together for this. This matches.
• Option C: Respiratory system (gas exchange) doesn't produce immune cells. Eliminate C.
• Option D: Muscular (movement) and nervous (control) systems don't produce/transport immune cells. Eliminate D.

Answer:

B. The skeletal and circulatory systems work together to produce and transport immune cells throughout the body.