Final answer:
The account payable system is not a primary component of a typical e-commerce site; it pertains to internal accounting, unlike the merchant account, payment gateway, and security system which are core to e-commerce operations.
Step-by-step explanation:
In the context of a typical e-commerce site, the primary components typically include the merchant account, which allows the business to accept credit and debit card payments; the payment gateway, which facilitates the transfer of information between a payment portal and the front-end processor or acquiring bank; and the security system, which is essential for protecting sensitive customer data and ensuring secure online transactions.
On the other hand, the account payable system is generally considered a component of the internal accounting system of a business rather than a primary component of an e-commerce site. The account payable system deals with the business's obligations to pay short-term debts to its creditors or suppliers.
Therefore, the correct answer is a) The account payable system, which is not one of the four primary components of a typical e-commerce site.