Which of the following are primary components of the human circulatory system?

• A. Stomach, intestines, and liver
• B. Kidneys, ureters, and bladder
• C. Heart, blood vessels, and blood
• D. Lungs, trachea, and bronchi

Answer: (C)

Verified step by step guidance

1. Step 1: Understand the human circulatory system's function, which is responsible for transporting oxygen, nutrients, hormones, and waste products throughout the body.
2. Step 2: Identify the primary components of the circulatory system. These include the heart (the pump), blood vessels (the pathways), and blood (the transport medium).
3. Step 3: Compare the options provided in the question. The stomach, intestines, and liver are part of the digestive system; kidneys, ureters, and bladder are part of the excretory system; lungs, trachea, and bronchi are part of the respiratory system.
4. Step 4: Recognize that the correct answer is 'Heart, blood vessels, and blood,' as these are the essential components of the circulatory system.
5. Step 5: Reinforce the concept by noting that the circulatory system works closely with other systems, such as the respiratory system, to ensure oxygen delivery and carbon dioxide removal.