A party who filed a financing statement covering inventory on April 1, 2012 would have a superior interest to which of the following parties?
a. A holder of a mechanic's lien whose lien was filed on March 15, 2012.
b. A judgment lien creditor who filed its judgment on April 15, 2012.
c. A holder of a purchase money security interest in after-acquired inventory filed on March 20, 2012.
d. A purchaser in the ordinary course of business who purchased on April 10, 2012.