Which of the Following Is a Primary Reason Why References

Which of the following is a primary reason why references should not be included unless asked for in a résumé?

A) It is extremely difficult for a person to find someone who will refer him or her.
B) It takes up space that a person could use to sell his or her skills.
C) It is unethical for a person to be selected for a job based on someone's reference.
D) It can always be given at a later point in time by putting "references available upon request" at the bottom of a résumé.
E) It is against the law to hire an individual based on his or her references.