How Does a Creditor Perfect His or Her Interest

How does a creditor perfect his or her interest?

A) By showing that he or she extended credit to the debtor prior to other creditors.
B) By showing that the debtor agreed to perfect his or her interest.
C) By contacting the bankruptcy court and letting it know that he or she is a priority creditor.
D) By filing appropriate paperwork to record his or her security interest.
E) All of the above.