Which of the following is a key benefit of using a three tier architecture in a client server database environment?

Introduction / Context:
Three tier architecture is a popular design pattern for client server applications, particularly those that use databases. It separates the system into presentation, application or business logic, and data layers. This separation brings several potential advantages, but not every desirable property is guaranteed in every implementation. This question asks you to identify a core benefit that is strongly associated with three tier architecture in the client server database environment.

Given Data / Assumptions:

We are discussing a three tier architecture with a client layer, a middle application server layer, and a database server layer.
Business logic is primarily located in the middle tier rather than in the client or database tiers.
The system may need to evolve as business requirements change, for example by adding new modules or services.
Generic claims about performance and thin clients should be evaluated carefully rather than assumed to be universal.
We want the option that best expresses a robust, widely accepted benefit of three tier architecture.

Concept / Approach:
A major advantage of three tier architecture is modularity. Because the business logic is separated from the user interface and the data storage, developers can add or modify modules in the middle tier to support new business requirements while leaving the client and database layers mostly unchanged. This makes the system more flexible and easier to maintain. Although three tier architectures can lead to better scalability and may enable thinner clients, performance improvements for compiled SQL statements and perfectly thin clients in every scenario are not guaranteed by the architecture itself.

Step-by-Step Solution:
Step 1: Recall that the three tier model divides an application into presentation, business logic, and data storage layers. Step 2: Recognize that because business rules are isolated in the middle tier, new features and modules can often be added by extending or modifying this tier without redesigning the database schema or deploying entirely new client applications. Step 3: Evaluate the options. The first option explicitly states that new modules can be built to support specific business needs, which is a direct consequence of this modular separation. Step 4: Notice that the other options make stronger or more absolute claims about performance or thinness that are not guaranteed by the architecture alone, and thus are less reliable as general benefits.

Verification / Alternative check:
Consider a web based system where browser clients interact with a web server that hosts business logic, which in turn communicates with a database server. When a new reporting module is needed, developers can implement it in the middle tier and expose new endpoints or user interface elements without changing how the clients connect or how the database stores data. This demonstrates how three tier architecture supports incremental growth through new modules. On the other hand, performance may improve or worsen depending on implementation details, so it is not a guaranteed universal benefit.

Why Other Options Are Wrong:
The claim that performance always improves for compiled SQL statements is too strong. Performance depends on indexing, query design, hardware, and many other factors. Three tier architecture does not inherently guarantee better performance for all compiled SQL.
The claim that it always results in a thinner client and database server oversimplifies reality. Some implementations may still have relatively complex clients or heavy stored procedure logic in the database layer.
The option that groups all statements as universal benefits is wrong because it bundles together claims that are not always true in practice.

Common Pitfalls:
A common pitfall is to treat architecture patterns as magic solutions that automatically solve performance or scalability problems. Another mistake is to push too much logic either into the client or into the database, undermining the benefits of separation in three tier design. Understanding that three tier architecture mainly improves modularity and maintainability helps set realistic expectations about what it can and cannot do.

Final Answer:
A key benefit of three tier architecture is that new modules can be built to support specific business needs without redesigning the entire system.