下列句子的标点符号使用正确的一项是[ ]

 A．为进一步增强北京文化软实力，充分发挥城市精神在城市建设中的导向和凝聚作用，北京市政府启动了《北京精神》表述语征集民意活动。     

B．“爱国、创新、包容、厚德”是一个有机整体，充分体现了城市精神与核心价值的相互协调，城市共性与北京个性的相互兼容，历史底蕴与未来取向的相互统一，城市特色与市民气质的相互融合，反映了北京特有的文化品位和首善特质。

C． 爱国，是北京精神的核心；创新，是北京精神的精髓；包容，是北京精神的特征；厚德，是北京精神的品质。

D．“包容既是北京市民海纳百川、雍容大度的胸襟和气度，”北京师范大学教授于丹说：“也是市政建设博采众长、兼容并包的思维方式，更是北京作为首都尊重差异、和谐共生的文化特质和独特品质。”

In January 2011 Department Store entered into a sales contract with Appliance Co to buy 100 refrigerators from the latter at a price of RMB 3,000 yuan/piece, total price being RMB 300,000 yuan. The payment would be made in two instalments: 100,000 yuan as advance payment to be paid after the conclusion of the contract, and the remaining 200,000 yuan to be paid in April 2011. Upon receiving the advance payment Appliance Co would deliver all the products. After the conclusion of the sales contract, Department Store made the first payment of 100,000 yuan and received all the products delivered by Appliance Co. In the same month, Appliance Co intended to rent a space of 100 m2 from Department Store to exhibit its other appliance products. For this purpose the two parties entered into a rental agreement and agreed upon the following terms and conditions: the term of rental would be one year as from January to December 2011; the total rental would be RMB 400,000 yuan and be paid RMB 100,000 yuan quarterly within the first 10 days of January, April, July and October. At the end of March 2011 Appliance Co sent Department Store a written notice, stating that it would set off its rental of RMB 200,000 yuan for the second and third instalments with the remaining price of 200,000 yuan for the refrigerators. Required: Answer the following questions in accordance with the relevant provisions of the Contract Law, and give your reasons for your answer:

(b) state the conditions to be met by Appliance Co when it was claiming the set-off of credit and debt with Department Store. (6 marks)