Millie lends Arthur, her next-door neighbor, 25,000 . He gives her his diamond ring as collateral ...

Millie lends Arthur, her next-door neighbor, 25,000 . He gives her his diamond ring as collateral for the loan. Which statement is true?
 a. Millie has no valid security interest in the ring because the parties did not enter into a security agreement.
  b. Millie has no valid security interest in the ring because she has not filed appropriate papers.
  c. Millie has an attached, unperfected security interest in the ring.
  d. Millie has an attached, unperfected security interest in the ring but can perfect her interest by filing.
  e. Millie has an attached, perfected security interest in the ring.