Final answer:
A valid DEA number is assigned by the U.S. Drug Enforcement Administration to healthcare providers authorized to prescribe controlled substances. The valid DEA number from the options given is AD5478316.
Step-by-step explanation:
A valid DEA number is a number assigned by the U.S. Drug Enforcement Administration to healthcare providers, including doctors, dentists, and veterinarians, who are authorized to prescribe controlled substances. It consists of two letters followed by seven numbers, with a check digit at the end. The check digit is calculated based on a specific algorithm using the other numbers in the DEA number.
Out of the options given, the valid DEA number is 4) AD5478316 because it follows the format of two letters followed by seven numbers. The other options provided do not conform to the structure of a valid DEA number.