*Question G2C08:
What prosign is sent to indicate the end of a formal message when using CW?*  

*Correct Answer is  C: AR*  

### AI Response: (may contain errors)  

To indicate the end of a formal message when using CW (Continuous Wave), the correct prosign is:

**Correct Answer: AR**

### Explanation:

1. **Why AR is correct:**
   - The prosign "AR" is used in CW to signify "End of Message" or "End of Transmission." It is a standard practice in amateur radio to indicate that the sender has finished their message and is awaiting a response.

2. **Why the other choices are incorrect:**
   - **A: SK** - This prosign means "Silent Key," which is used to indicate that a station is no longer operational or that the operator has passed away. It is not used to end a message.
   - **B: BK** - This prosign stands for "Break" and is used to indicate that the sender is inviting a response or interruption. It does not signify the end of a message.
   - **D: KN** - This prosign means "Go ahead, station(s) called," and is used to direct a specific station to respond. It does not indicate the end of a message.

### Summary:
- Use "AR" to end a formal message in CW.
- "SK" indicates a silent key, "BK" invites a response, and "KN" directs a specific station to reply. 

Understanding these prosigns is essential for effective communication in amateur radio.