Which of the following statements is true regarding constants in programming?

The statement about constants that holds true is that they cannot be altered during execution. This means that once a constant is defined within a program, its value remains fixed throughout the program's runtime. This characteristic is crucial because it helps maintain the integrity of data—ensuring that certain values remain unchanged when needed.

In most programming languages, constants are defined to represent fixed values that should not be modified. For example, declaring a constant for mathematical constants like Pi ensures accuracy in calculations that depend on this fixed value. This immutability is essential in various scenarios, such as using configuration values that should not accidentally change during program execution.

Understanding the nature of constants helps programmers design systems that rely on steadfast values, preventing unexpected behaviors that could arise from unintentional modifications. Thus, the essence of constants is their permanence, making them a vital concept in ensuring code reliability and clarity.