Central Maine Power Co$.($CMPC$)$ made a promotional offer in which it promised to pay a substantial sum to any homeowner or builder who constructed new housing with electric heat. To qualify for the offer, Motel Services, Inc. $($MSI$)$ decided to install electrical heat in a housing project it was constructing in Waterville, Maine. MSI built the units and requested payment for the full amount of the promotional offer. Is CMPC obligated to pay? Why or why not?

a$.$ No$,$ CMPC is not obligated to pay because this was a bilateral contract, and MSI did not promise to perform.

b$.$ Yes, CMPC is obligated to pay because this was a unilateral contract, and MSI performed.

c$.$ Yes, CMPC is obligated to pay because this was a bilateral contract, and MSI performed.

d$.$ No$,$ CMPC is not obligated to pay because MSI did not make a serious offer