Final answer:
The condominium's main entry door's additional security feature includes restricted key duplication, ensuring unauthorized copies are not made to enhance security. So, the correct answer is option A. No duplicates for the key.
Step-by-step explanation:
The main entry door of a condominium may feature an additional security feature such as keys that cannot be duplicated (no duplicates for the key) or a restriction where only one company is allowed to do the duplication (only one company for duplication).
These security measures ensure that unauthorized copies of the key are not made, which enhances the overall security of the condominium. To further increase security, condominiums may also use electronic key fobs or access codes that are difficult to duplicate and can be easily deactivated if lost or stolen.
Therefore, the correct answer to the given question is option A. No duplicates for the key.