This task is obligatory.
Do you think military service should be obligatory?
All subjects on the list are obligatory, you can choose extra subjects to study on top of them.
This insurance is obligatory
is english your optional subject or obligatory?
It isn’t obligatory to stay. Let’s go home.
Which subjects are obligatory?
Going to school is obligatory for all children
Wearing safety shoes is obligatory.
The attendance is obligatory.
If school wasn't obligatory, I would stop going there.
Presence of all members is obligatory.