For a payment method to be available in the admin panel (backend), the configuration must explicitly allow its internal use. This is controlled by the can_use_internal flag in config.xml.
* Configuration for Admin Use:
* The can_use_internal flag determines if a payment method is available for admin users when placing orders from the backend. By default, this is often set to false for some custom payment methods, meaning they won't appear in the admin.
* Why Option C is Correct:
* Setting can_use_internal to true makes the payment method available for backend order creation, which is why this is the most probable reason it isn't visible in the admin.
* Options A and B do not influence the payment method's availability in the admin; they affect verification types and capture settings, respectively.