Answer:
A ¡Hola amigo!
B. Con un agente de inmigración se usaría tú.
C. Con un agente de inmigración se usaría Ud.
D. ¿Cómo estás?
Step-by-step explanation:
The use of "you." is an abbreviation for "usted", which is a respectful way of addressing someone in Spanish. In formal or professional situations, such as when dealing with immigration agents, it is important to keep the conversation respectful and formal.