Final answer:
The best site to attempt a multi-draw venous sample for a CPCT is the median cubital vein, located in the antecubital region, which links the cephalic and basilic veins.
Step-by-step explanation:
When collecting a multi-draw venous sample, the Certified Patient Care Technician (CPCT) should attempt to draw from the superficial vessel located in the antecubital region that links the cephalic vein to the basilic vein in the form of a 'V'. This vessel is often referred to as the median cubital vein and is a frequent site from which to draw blood due to its accessibility and size. It is imperative to locate a well-distended vein to minimize discomfort and ensure an adequate sample can be obtained.