Question

which body part belongs to the circulatory system?
a. diaphragm
b. heart
c. trachea
d. kidney

Explanation:

The circulatory system's main organ is the heart, which pumps blood. The diaphragm (A) is part of the respiratory system (helps in breathing). The trachea (C) is also part of the respiratory system (air passage). The kidney (D) is part of the excretory system (filters waste). So, the heart (B) belongs to the circulatory system.

Answer:

B. heart