Kay, an art collector, promised Hammer, an art student, that if Hammer could obtain certain rare artifacts within two weeks, Kay would pay for Hammer’s postgraduate education. At considerable effort and expense, Hammer obtained the specified artifacts within the two-week period. When Hammer requested payment, Kay refused. Kay claimed that there was no consideration for the promise. Hammer would prevail against Kay based on:

a. Unilateral contract

b. Unjust enrichment

c. Public policy

d. Quasi contract Appendix