Question

when is it appropriate to use acronyms and emoticons in business communication?
when the receiver of the message knows what they mean
when the receiver of the message will not have much time to read the message
when the sender of the message wants to show they know the business lingo
when the sender of the message is running short on time

Explanation:

In business communication, acronyms and emoticons should be used when the receiver understands them to avoid confusion. Using them when the receiver has little time doesn't guarantee understanding. Showing knowledge of jargon isn't the main reason, and the sender's time - constraints aren't relevant to appropriate usage.

Answer:

When the receiver of the message knows what they mean