Choice "B" is correct. To be an express warranty, the language must be part of the basis of the bargain.
Choice "c" is incorrect. An express warranty arises from any statement of fact or promise made by the seller, any description of the goods made by the seller, or any sample or model shown by the seller at a time when it could have become part of the basis of the bargain.
Choice "d" is incorrect. An express warranty may be made orally, in writing or by conduct (e.g., the showing of a model).
Choice "a" is incorrect. Express warranties can arise from any description of the goods given to the buyer before the contract is executed.