Final answer:
To measure the number of white blood cells, a doctor would order a complete blood count (CBC). This test provides essential insights into the blood's cellular composition. Therefore, the correct answer is D, complete blood count.
Explanation:
Identifying the Right Test for White Blood Cell Count
If a doctor wants to assess the number of white blood cells (WBCs) in a patient's blood, he or she would typically order a complete blood count (CBC). This test provides critical information about the cells in the blood, including levels of red blood cells, hemoglobin, and white blood cells.
The options provided are:
- A. urinalysis - This test examines urine and is not used for blood components.
- B. comprehensive metabolic panel - This test primarily assesses the chemical balance and metabolism of the body and does not measure WBCs directly.
- C. MRI - This imaging technique is used for visualizing internal structures and does not measure blood cell counts.
- D. complete blood count - This test is specifically designed to count different types of blood cells, including white blood cells.
Therefore, the correct answer is D, a complete blood count, as it is specifically designed to measure the number of white blood cells in the blood.
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