Final answer:
To prevent coring, a technician must enter the vial with their needle at a 45-degree angle.
Step-by-step explanation:
The correct answer to the question is b. 45°. To prevent coring, a technician must enter the vial with their needle at a 45-degree angle. This angle helps to minimize the chances of piercing the rubber stopper at the top of the vial and causing a core sample to be extracted instead of the desired liquid sample.