On march 1, green went to easy car sales to buy a car. green spoke to a salesperson and agreed to buy a car that easy had in its showroom. on march 5, green made a $500 down payment and signed a security agreement to secure the payment of the balance of the purchase price. on march 10, green picked up the car. on march 15, easy filed the security agreement. on what date did easy’s security interest attach?
a. march 1.
b. march 5.
c. march 10.
d. march 15

Employees at a library check out books to patrons. books have an isbn and a name. the library sometimes has multiple copies of the same book. books have one or more authors. a patron is an individual who has an active (non-expired) library card. for each library card, we store the person's first and last names and their address. for each employee, we store their employee id, current salary, first and last name and their address. we also store the employee id of their current manager. each time we check out a book to a patron we need to store the date of the transaction, the employee who checked out the book to the patron, and the library card of the patron. some employees have library cards. if an employee patron turns in a book late, the fine that they pay is a percentage of their salary. some employees are authors who have library cards—they are allowed to check out as many books as they like.