A. is the answer.
Another name for a dependent entity is a weak entity.
A weak entity is an entity whose primary key contains a foreign key back to another entity.
For example, in this model:
Student Grade is a weak entity. Student Grade’s primary key contains the primary keys from Class, Semester, and Student.
How would you bring back a single Final Grade value? To bring back a single grade of ‘B’ for example, you would need to know who received the ‘B’ (Student ID), what class did he/she get the ‘B’ in (Class Code), and when the student received the ‘B’ in this class (Semester Code).