The correct code snippet to ensure that the Cisco NX-OS scheduler runs every day at 3:00 a.m. is "time daily
3:00". This command configures the scheduler to execute the specified job daily at the given time, without the need for a 'start' keyword, which is not required in the syntax for daily repetitive tasks.
References: This explanation is based on the Cisco NX-OS documentation, which provides guidelines on how to schedule tasks using the NX-OS scheduler feature. The documentation is part of the Cisco Data Center Core Technologies study materials.