Final answer:
In e-commerce transactions, the N-tier architecture is the most commonly used structure due to its scalability, flexibility, and manageability, which are suitable for e-commerce platforms' needs.
Step-by-step explanation:
The structure most commonly used in e-commerce transactions is N-tier. This architecture allows for a more scalable, flexible, and manageable system which is ideal for handling the complex and variable demands of e-commerce platforms. An N-tier application divides the entire structure into various tiers, which usually includes a presentation tier for the user interface, a middle tier for business logic, application servers, and web services, and a data tier for data storage and retrieval. This separation of concerns across multiple levels provides for greater security and the ability to independently update or modify each tier without affecting others.
In contrast, a 2-tier architecture is more straightforward, consisting just of a client and server, and is less commonly used for large-scale e-commerce due to its limitations in scalability and security. Fat client and thin client refer to client-side configurations where a fat client does substantial processing on the client side, and a thin client relies more on the server. These are not architectures but rather descriptions of the client's capabilities within the overall system.