On May 1, Buffalo Corp. signed a loan agreement in which Kyle Bank promised to lend Buffalo $1 million. On May 15, Buffalo signed a security agreement covering 100,000 shares of Buffalo stock. Then on May 18, Kyle Bank wired the $1 million to Buffalo. On May 21, Buffalo used the $1 million to buy equipment. The shares of Buffalo stock were delivered by Buffalo to Kyle Bank on May 22.

A. When did Kyle Bank attach a security interest in the shares of Buffalo stock?

B. Is Kyle Bank's security interest a purchase money security interest?

C. Is Kyle Bank's security interest perfected? If yes, how? If no, why not?