Final answer:
The normal cardiac output (CO) in an adult has a mean of 5.25 L/min, with a normal range of 4.0 to 8.0 L/min from each ventricle, resulting in answer option B (5 to 7 L/min) being correct for total heart CO under resting conditions.
Step-by-step explanation:
The normal cardiac output (CO) in an adult is usually given as a range. According to the information provided, the mean CO is 5.25 L/min, with a normal range of 4.0 to 8.0 L/min. This range refers to CO from each ventricle separately, which means that the total CO for the heart is the sum of the output from both ventricles. Considering this information, the correct answer to the student's question is B. 5 to 7 L/min as the closest range for normal CO in an adult. It's important to remember these figures can vary based on several factors like physical activity levels. For instance, during vigorous exercise, CO can increase significantly as the heart rate (HR) and stroke volume (SV) increase to meet the body's demands for oxygen and nutrients.