Which of the following fulfillment solutions is available to vendors, rather than sellers, who sell on Amazon.com?

Direct Fulfillment is the correct answer because it is a fulfillment solution available specifically to vendors who sell on Amazon.com. In the Direct Fulfillment program, vendors ship products directly from their own warehouse to customers, bypassing Amazon's fulfillment centers. This program is designed for vendors who want to maintain control over their inventory and fulfillment processes while still leveraging Amazon's platform for processing orders and customer service. On the other hand, Fulfillment by Amazon (FBA) and Seller Fulfilled Prime (SFP) are fulfillment solutions available to third-party sellers, not vendors, where Amazon either handles the storage and shipping or allows sellers to fulfill Prime orders themselves.