A department store made an announcement in the local newspaper to launch a bonus sale promotion in July 2008. Under this promotion plan any consumer who bought commodities for RMB 200 yuan would be granted one bonus coupon with a particular number for a lucky-draw. The lucky-draw would be made publicly on 31 July 2008. During July Mr Zhou received five coupons for buying commodities totalling more than RMB 1,000 yuan in the department store.On 31 July 2008 the department store made the lucky-draw in public and announced all the numbers of coupons in winning the bonus.On 2 August 2008 the department store put a written notice on the notice board in the front of its premises, stating that the winners should come to cash the bonus before 10 August 2008, otherwise they should be regarded as automatically giving up the bonus.On 12 August 2008 Mr Zhou got to know the lucky number on one of his coupons was the same as the lucky number for the first class bonus of RMB 5,000 yuan. He went to the department store to cash the bonus but was refused by the department store on the grounds that he was too late to take the bonus.Required:Answer the following questions in accordance with the relevant provisions of the Contract Law of China and give your reasons for your answers:
(a) State the legal nature of the announcement for the bonus sale promotion by the department store. (2 marks)