During software testing, what data type is used when you check for limits?

The correct choice involves the use of "Extreme data" during software testing to check for limits. Extreme data refers to the maximum and minimum boundaries of input values that a software application can handle. Testing with extreme data is crucial as it helps to identify how the software behaves at these limits, ensuring that it can process edge cases effectively without crashing or producing erroneous results.

For example, if a program is designed to accept integers between 1 and 100, testing with extreme data would involve using the values 1 and 100, as well as values just outside this range, such as 0 and 101. This type of testing verifies that the application can handle both the lowest and highest valid inputs, and permits developers to discover any potential issues related to data overflow, boundary conditions, or off-by-one errors that could arise when operating at the limits of the specified input range.

The other data types mentioned, such as erroneous data, valid data, and invalid data, serve different purposes in software testing. Erroneous data might be used to find how the software handles outright mistakes or incorrect inputs. Valid data is typically within the acceptable range that the application is meant to process, while invalid data is those inputs that explicitly do not meet the application's criteria.