Brightlights Ltd, a Lighting and Electrical Company, Run a TV

Multiple Choice

Brightlights Ltd, a lighting and electrical company, run a TV commercial at lunchtime on Monday offering special snail-shaped lamps free 'to any of our customers who buy a new chandelier in our Spring sale and send proof of purchase to our head office'. They also publish the offer in the Daily Comet. In which situation would Brightlights' unilateral offer have been validly revoked before Dora's acceptance?

A) Dora sees the advert in her Monday morning copy of the Daily Comet and decides to buy a chandelier. On Tuesday, Brightlights Ltd runs a TV commercial saying 'Spring sale now ended - even bigger bargains in our Summer sale'. Dora does not see this, and buys a chandelier from Brightlights' Dorking branch on Wednesday. She sends a copy of her receipt to the head office, and receives a note back saying that the offer has ended.
B) Tom notices the advertisement in the Daily Comet and circles it. He does not have a car, and it is snowing, so he puts on his ski boots and immediately sets out for his local Brightlights store. En route, after walking for an hour, he is knocked down by a lorry and spends four days in hospital. On Friday, he reads in the Daily Comet that Brightlights' New Year's sale has now ended but attempts to buy the chandelier anyway.
C) Sally rings up Brightlights' head office and leaves a message saying that she has seen their commercial and could they please reserve two snail lamps for her.