对于经营性物业以及租赁为主的高档居住物业的物业管理，下列说法正确的有（）。

A.物业管理的准则是出租经营与管理服务并重

B.业主通过定期收取租金或上缴承包金的方式收回投资

C.物业管理企业拥有物业的管理权，不拥有物业使用权的经营权

D.租赁合同管理是物业合同管理中的重点

E.物业类型主要包括写字楼、商厦、综合楼、高级公寓、别墅等

On 3 March 2008, Azman wrote to Benny offering to sell to Benny his yacht, Lightning, for RM1 million. The letter expressly stated that if Benny did not reply by 10 March 2008, he would be deemed to have accepted the offer.On 9 March 2008, Azman sent a letter to Benny revoking his offer. On 10 March 2008 Benny posted a letter to Azman accepting Azman’s offer. Azman’s letter of revocation reached Benny on 11 March 2008. Benny’s letter of acceptance reached Azman on 12 March 2008.Benny wishes to know whether there is a valid contract between him and Azman for the sale and purchase of the yacht, Lightning.Required:Advise Benny under the law of contract. (10 marks)