Which of the following statements describes a key principle of software testing?

The statement that describes a key principle of software testing is that it is normally impossible to test all input and output combinations for a software system. This principle recognizes the inherent complexity and variety in software applications. Given the vast number of possible inputs and outputs, along with different execution paths and system states, exhaustive testing becomes impractical. Instead, effective testing focuses on risk-based approaches, prioritizing critical functionalities and high-risk areas to validate software quality while acknowledging that not every possible scenario can be covered. This understanding drives the use of techniques like equivalence partitioning and boundary value analysis to maximize test coverage within feasible limits.