Option B is the correct answer because it describes the fastest route to establishing the data needed for checkout development when setting up a new store. The developer can use sfdx setup scripts to deploy a Lightning B2B testing environment that includes checkout flows, sample products, and a buyer. This way, the developer can quickly and easily test and customize the checkout flow using Experience Builder or Flow Builder. The other options are incorrect because they either require more time, manual steps, or additional tools to set up the data for checkout development. For example, importing a previously exported store archive or using data loader would require the developer to have access to the source data and the target org, and to map the fields and objects correctly. Selecting Add Sample Data when setting up the store would only provide a limited amount of data that may not be sufficient for checkout development. References: Create a B2B Commerce Org and Checkout Flow, B2B Commerce on Lightning Experience Developer Guide, B2B Commerce and D2C CommerceDeveloper Guide