How can you create a constant variable in C++?

To create a constant variable in C++, the 'const' keyword is used during the declaration. This keyword indicates that the variable's value cannot be changed after it has been initialized. For example, if you declare const int myNumber = 5;, this means that myNumber cannot be modified in any subsequent statements such as myNumber = 10;.

The use of 'const' is critical in programming for maintaining constants that should remain unchanged throughout the program, ensuring data integrity and helping prevent accidental modifications. This is particularly useful in scenarios where certain values need to be protected, such as configuration settings or mathematical constants.

Other options do not correctly represent how to create a constant variable in C++. The 'immutable' keyword does not exist in C++, and there are no provisions for declaring a variable as 'static' to make it constant; 'static' pertains to the duration and linkage of the variable but doesn't prevent its value from being modified. Initializing a variable without declaration does not define it as a constant either; such a practice would lead to ambiguity in how the variable is treated in the program.