This is the 5443rd most frequent Spanish word.
obligatoria
Mandatory.
The word 'obligatoria' is used to describe an action that is required or mandated, functioning as an adjective describing 'la asistencia' (attendance).
La asistencia a la reunión es obligatoria.
Attendance at the meeting is mandatory.
Here, 'obligatoria' modifies 'la educación primaria' (primary education), indicating it is a state-enforced requirement.
La educación primaria es obligatoria para todos los niños.
Primary education is compulsory for all children.
'Obligatorio' (masculine form for agreement with 'el uso') highlights the necessity imposed for safety considerations.