Helene sends an instant message to the sender so that he or she knows that the message was received and understood. helene is engaged in

I believe the answer is: Feedback

in communication, feedback refers to the response that we have after receiving a certain message. For the giver of the message,feedback could be used as some sort of confirmation to ensure that the receiver is not confused about the content of the message.

imperial crisis leads to civil war.

roman forces withdraw from britain as goths attack rome.

odoacer topples romulus augustus

huns attack the empire and drive german peoples ahead of them.

could you go a bit more in depth with you question? it's quite hard to understand. as soon as you do that i will be glad to : )