$10.$ Albert read ElectroCorp$$s ad in the local newspaper, advertising a music system for $$89.$Albert rushed to the store to buy the system only to be told by the salesperson that the ad was a misprint and the price should have been $$289.$Albert gave the salesperson $$89$ plus sales tax and demanded the music system.

a$.$ The ad is a firm offer by the merchant, and the music system must be sold for $$89.$

b$.$ The ad is a contract and the store must abide by terms stated in the contract.

c$.$ The store must accept the price stated in the ad$,$ but only if Albert has a copy of the ad with him.

d$.$ Albert is merely making an offer to ElectroCorp to buy the music system for $$89$ plus sales tax.