Answer: d. both Iris and Daphne will want to purchase Joss's services but Joss will not be willing to undertake the job.
Explanation:
Iris will want Joss's services but they will be unable to afford them as Iris is only willing to pay $500 whereas Joss wants $1,200 for the job.
The same goes for Daphne who is only willing to pay $800.
Both of them will therefore want to hire Joss but will be unable to.
Joss could however charge both of them their willingness to pay and then sum the cash up and give them both the research whilst still making a profit.