Which of the following keystrokes or characters is sent as part of ARQ communications to switch information transmission control from one station to the other?

Correct Answer: Option A — +?

The character sequence '+?' is the standard command in ARQ (Automatic Repeat Request) mode to request a 'Go Ahead' (GA) signal from the coast station. This signals the station to switch the information transmission control, allowing the ship to proceed with its specific telex traffic request.