In the provided program, what is the scope of the variable 'a'?

The variable 'a' has block scope if it is declared within a block of code, such as within curly braces { }, which is a common practice in programming languages like C, C++, or Java. Block scope means that the variable is only accessible within the confines of that specific block, ensuring that its visibility and lifetime are limited to that section of the code. This is beneficial for controlling namespace and preventing variables from conflicting with one another in larger blocks of code or across multiple functions.

In contrast, variables declared with function scope would exist throughout the entirety of the function they are declared in, while global scope indicates accessibility throughout the entire program. Function-prototype scope, which is a concept in languages like C and C++, refers specifically to variable declarations that can be used within the prototype of a function but does not apply to regular variable declarations within the function body or blocks of code. Thus, if 'a' is indeed declared within a block, its restricted access is what defines it as having block scope.