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When using performance or function specification as a method of description: O a. the opportunity exists to purchase identical requirements from several sources. O b. it is fairly easy to ensure that suppliers are quoting for exactly the same material or service. O c. most of the risk is borne by the supplier. O d. it is easy to compare quotations and the supplier cannot include a risk allowance in the price. O e. most of the risk is borne by the buyer