Final answer:
Veterinary technicians can administer and manage controlled substances but cannot prescribe them without a veterinarian's supervision.
Step-by-step explanation:
The duties of the veterinary technician as related to controlled substances typically include administering controlled substances to animals, ensuring proper storage and record-keeping, and educating clients on the use of these substances for their pets. The one duty that does not fall under the responsibility of a veterinary technician is prescribing controlled substances without veterinary supervision. Prescribing medications is a task that requires a veterinarian's authorization and veterinary technicians cannot prescribe medications independent of a veterinarian.