Announce over the loudspeakers, "The campus is now secure. Please return to your classrooms."

Designate zones according to the alphabet and direct students to the zones based on their last names to reunite them with their parents.

Require parents to pass through metal detectors and then allow them to look for their children in the school.

Ask police to encircle the school campus with yellow tape to prevent parents from entering.

The correct answer is: b) Designate zones according to the alphabet and direct students to the zones based on their last names to reunite them with their parents.