Ava substantially performs her contract to build a spare bedroom for Sinclaire but has been unable to secure the building materials needed to finish the job despite her best efforts. Sinclaire is

a.) not required to pay Ava until the job is completed

b.) not required to pay Ava until she obtains the needed supplies

c.) required to pay Ava the amount due under the contract

d.)required to pay Ava the amount due under the contract less the cost of completing the job