Final answer:
A phlebotomy technician should immediately notify the provider for a WBC count of 1.8/mm³, which is substantially below the normal range, indicating potential medical concerns.
Step-by-step explanation:
A phlebotomy technician using a point-of-care test system to determine a patient's WBC count should immediately notify the provider if the result is A. 1.8/mm³. This value is significantly below the general reference range for a healthy WBC count, which is typically between 3.5 and 11 x 10⁹ cells/L. A low WBC count, known as leukopenia, can indicate an underlying problem with the patient's immune system or bone marrow and might necessitate further medical investigation and treatment.