Final answer:
The PCT should draw the Green-top tube first because it is commonly used for collecting a chemistry panel and coagulation studies.
Step-by-step explanation:
The PCT should draw the Green-top tube first.
When collecting a chemistry panel and coagulation studies, the green-top tube, also known as the sodium heparin tube, is commonly used. It contains an anticoagulant called sodium heparin, which prevents the blood from clotting. This tube is used for tests that require plasma, such as coagulation studies.
The other tubes mentioned, such as the red-top tube (for serum) and the lavender-top tube (for complete blood count), may be drawn after the green-top tube, depending on the specific tests being performed.