On Monday, Neil tells Outdoor Landscaping, Inc., that he will pay Outdoor $$500$ if a variety of tasks are completed by Friday. On Wednesday, when Outdoor is more than half done with the work, Neil says that he has changed his mind. Under the present$-$day view, these parties had

a$.$ a quasi contract when Neil said that he would pay for certain work.

b$.$ no contract.

c$.$ an expired contract when Neil said that he had changed his mind.

d$.$ a unilateral contract as soon as Outdoor began to perform.