Shim types are used in unit testing to isolate the code under test by diverting calls to specific methods to code that is defined in the test itself. This allows for consistent control over test conditions and returns predictable results irrespective of external factors, making it easier to test code that interacts with sealed classes, which cannot be inherited from and therefore cannot be stubbed easily.


The correct unit test should use the [TestMethod] attribute, which is essential for marking the method as a test method in the test framework. The Assert.AreEqual method should be used to verify that the expected value (finalBalance) and the actual result of the method call (result) are equal. Option C correctly uses the [TestMethod] attribute and Assert.AreEqual to compare the expected and actual values.

Using QueryString to store search terms and page index is the best approach because it allows the state information to be maintained across multiple browser sessions and different server networks. It also ensures compatibility with various browsers since the information is passed within the URL. This approach makes the application stateless on the server side, which is particularly useful in a load-balanced environment.
To handle web server failures gracefully and ensure servers in a web farm share state information, you should implement a state server for session state management. A state server allows session data to be stored out-of-process, on a separate server, which means session data is not lost if a web server fails, and it can be shared across multiple web servers. Options like InProc sessions are unsuitable for web farm environments because session data is stored in the memory of an individual web server, risking data loss and inconsistency among different servers. Cookieless sessions and web gardens do not provide mechanisms to share session state consistently across multiple servers in a web farm.