Jeremy promises Gillian a job if she moves to California for the job. Gillian, excited for the new job, quits her current job and moves across the country to California in reliance on Jeremy's promise of the new job. Jeremy, however, tells Gillian once she gets to California, he has no job for her. Which doctrine might Gillian use to sue Jeremy?

Unjust agreement

Promissory estoppel

Quasi contract

Equitable estoppel

Promissory enforcement