Staff, Inc., a flour wholesaler, contracted to deliver to Eclaire, a producer of fine baked goods, her flour requirements for a one-year period. Before delivery of the first scheduled installment, Staff sold its business and "assigned" all of its sale contracts to Miller, Inc., another reputable and long-time flour Miller, Inc., another reputable and long-time flour wholesaler. Staff informed Eclaire of this transaction. For this question only, assume that Eclaire accepted Miller's delivery of the first installment under the Staff-Eclaire contract, but that Eclaire paid the contract price for that installment to Staff and refused to pay anything to Miller. In an action by Miller against Eclaire for the contractual amount of the first installment, which of the following, if any, will be an effective defense for Eclaire? I. Eclaire had not expressly agreed to accept Miller as her flour supplier. II. Eclaire's payment of the contractual installment to Staff discharged her obligation. III. Staff remained obligated to Eclaire even though Staff had assigned the contract to Miller. 
I only. II only. I and III only. (C) I and III only. Neither I nor II nor III.