We can choose classes. Even though there are mandatory subjects that we all need to learn. We may perform poorly in all subjects. But we will have the basic knowledge in all subjects.
We can choose classes, although it is compulsory that we all need to learn. We may not do well in all subjects. But we do have a basic knowledge in all subjects.
We can choose the subject. Although it is not required that we all need to study. We can't do it well in all the subjects. But we have the basic knowledge in all subjects.