A seller accepts an offer conditional on the sale of the buyer's existing home within 60 days, with a 72-hour clause. Three weeks later, the seller receives a better offer. What rights does the seller have under the 72-hour clause?

Option C correctly describes the 72-hour clause mechanism under Canadian real estate law. When a seller receives a competing offer, they can serve notice to the conditional buyer requiring them to waive their condition within 72 hours or the agreement becomes void. This process is mandated by provincial real estate legislation and standard form agreements. The seller cannot simply void the agreement unilaterally but must follow the proper notice procedure, giving the original buyer the opportunity to remove their condition and proceed with a firm sale. This balanced approach protects both parties' rights while allowing market dynamics to function effectively.