The sender states the task but does not define the success criterion. What difficulty will the receiver face?

Correct answer: Determining whether the task is completed correctly

A task instruction tells the receiver what to do, but a success criterion explains what an acceptable result looks like. Without that standard, the receiver may complete the activity yet remain unsure whether the quality, quantity, time, or format is correct. The difficulty is therefore evaluating completion, not identifying the sender, choosing the channel, or receiving the message.