A: Single SKU Bundle. This is because the Multiple SKU Bundle type uses the Shopify Draft Order system as a basis. As soon as this system is used in any given transaction, the Shopify platform will automatically disable the Discount Code bar and only give discount control to the system related to Draft Orders (which, in this case, is the Multiple SKU Bundle type). Therefore, if you would like to offer discount codes with a bundle, please use the Single SKU Bundle type.