Which of the following statements is correct about constants?

Constants in programming are entities whose values cannot be altered after they have been assigned. The statement that correctly describes this characteristic is that a variable can be made constant by using the final reserved word when declaring it. This ensures that once a value is assigned to the variable, it cannot be modified throughout the program. For instance, if you declare a constant like final int myConstant = 10;, any subsequent attempt to change myConstant will result in a compile-time error.

Using final is a common practice in many programming languages, as it provides a way to define immutable values, promoting safer and more readable code. This is particularly useful in contexts where certain values are meant to remain constant, such as configuration settings or mathematical constants.

Other choices do not accurately describe the nature of constants. The misunderstanding that the compiler ignores constants declared in lowercase highlights a misconception, as the compiler recognizes constants regardless of their case, but using capital letters is just a convention to signal that a value should not be changed. The other options suggest that constants can be modified or have specific limitations that aren't aligned with the fundamental principle of how constants function. Thus, making a variable constant through the use of final is the correct approach.