Which file logs console messages that are related to system startup?

The file that logs console messages related to system startup is indeed /var/log/boot.log. This file specifically captures the output generated during the system's boot process, providing insights into the services that start, any errors that occur, and the overall status of system initialization. This makes it a critical resource for troubleshooting startup issues and understanding the boot sequence of the system.

In contrast, while /var/log/messages and /var/log/syslog do contain logs that may include some startup information, they are not exclusively dedicated to system startup events. Instead, they encompass a broader range of system messages throughout runtime, including kernel messages and user activity, which makes them less focused in this context.

The /var/log/startup.log file does not typically exist in standard Linux distributions, making it an incorrect choice. Therefore, /var/log/boot.log is the most appropriate option for logging console messages specifically related to system startup.