Buyer and Seller entered into a sales contract which stipulated that Seller should, on or before 10 January 2009, sell a shipment of personal computers (PCs) at a price of 300,000 yuan to Buyer, who should arrange transportation and pay the full price upon taking delivery. For the purpose of launching a market promotion plan at the end of 2008, Buyer asked Seller to provide the goods 20 days before the due date. Seller disagreed with the request since its capacity to process the PC was unable to meet the needs of Buyer. Under such a circumstance, Buyer made efforts to find PCs from other sources, and then transferred the original sales contract to a third party – Company X – with discount. Buyer did not inform Seller of this. On 8 January 2009 Company X despatched a truck to Seller to pick up the PCs under the sales contract. However, Seller refused to provide the PCs on the grounds that there was no contract between Company X and Seller. Required: Answer the following questions in accordance with the relevant provisions of the Contract Law of China, and give your reasons for your answer: (b) State whether the transfer of the sales contract by Buyer to Company X was valid. (5 marks)