While not at home, a landscaping crew mistakenly does work on your yard. By asking your neighbors, you determine which landscaping company did the work. You call the company to inform them that you did not contract with them to do yard work and they did your yard by mistake. A week later, you are sent a bill for the work done. Will you have to pay the bill?

No$,$ because quasi$-$contract theory does not apply here because you did not have knowledge of the benefit.

Yes, because you were unjustly enriched.

Yes, because you called them and accepted the work then.

No$,$ because promissory estoppel applies.