What is the first step when departing from a designated school bus stop?

The first step when departing from a designated school bus stop involves ensuring the safety of all students who may be boarding or have just disembarked from the bus. This primarily includes accounting for all students to confirm that no one is left behind or in the path of the bus. Once all students are accounted for, the bus driver can then safely transition from the bus stop.

Engaging the transmission and releasing the parking brake is a procedural task that comes after ensuring all safety measures are in place. The correct action sequence emphasizes the importance of student safety first and foremost, which is vital when operating a school bus. This approach ensures that the driver is mindful of the children around the bus and prevents any potential accidents as the bus prepares to leave.

Other options might suggest steps that either misplace safety checks or put the vehicle into motion before ensuring all students are properly accounted for, which does not prioritize safety in the way that the correct choice does.