Final answer:
The phlebotomy technician should select the medial cubital vein in the left arm for collecting the blood specimen from a patient who had a right-sided mastectomy.
Step-by-step explanation:
The phlebotomy technician should select the medial cubital vein in the left arm for collecting the blood specimen from a patient who had a right-sided mastectomy.
The median cubital vein is the most common site for drawing venous blood in humans. It is located in the antecubital region, which is the area located in the bend of the elbow.
The right-sided mastectomy would have likely affected the blood flow and drainage in the right arm, making it less ideal for phlebotomy. Therefore, the technician should choose the left arm instead, as it would be a more suitable option.