possible error in SCBCD prep question?

[Uchana Jackson]

You write two entity classes with bi-directional many-to-many relationship between them.
 
The Faculty class is written as follows:
 
@Entity
public class Faculty {
Collection students;
Collection subjects;
//more code
}
 
The Students class is written as follows:
 
@Entity
public class Student{
Set<Faculty> faculty;
Collection subjects;
//more code
}
 
Which of the following set of annotations will you use to specify the association b/n the classes?
 
choose two.
 
A: @ManyToMany(targetEntity=Student.class) on the students field.
B: @ManyToMany on the students field.
C: @ManyToMany(mappedBy="faculty") on the student field.
D: @ManyToMany(mappedBy="faculty") on the faculty field.
 
Answer options A and D are correct.

/**************************************************************/

Please explain to me why option D is correct. I do not understand how mappedBy="faculty" is the inverse side of the relationship.

Perhaps option D should read as follows:

@ManyToMany(mappedBy="students")

on the faculty field. Also why is option C incorrect?

According to JPA book by Mike Keith:

"No matter which side is designated as the owner, the other side should include the mappedBy element, otherwise the provider will think that both sides are the owner and that the mappings are separate unidirectional relationships."

page 102

also see the example on page 101.