Final answer:
Citizens and diplomats were immediately processed and able to enter the country upon arrival.
Option AD.
Step-by-step explanation:
The passengers who were immediately processed and able to enter the country upon arrival are:
- Citizens: Citizens have the right to enter their own country without restriction. They may need to present their passport or other identification, but they are not subject to visa requirements.
- Diplomats: Diplomats are representatives of foreign governments and are granted diplomatic immunity. They are usually able to enter the host country without extensive immigration procedures.