How is a variable declared in C++?

In C++, declaring a variable involves specifying its data type followed by the variable name. This approach informs the compiler about the kind of information the variable will hold, such as whether it is an integer, a floating-point number, or a character. For example, if you want to declare an integer variable named "age," you would write int age;. By explicitly stating the data type, the compiler can allocate the appropriate amount of memory and enforce type constraints during program execution.

The other choices do not accurately describe the correct way to declare a variable in C++. Specifying only the variable name does not provide the necessary information for the compiler to recognize the variable's type or how to handle it. Defining the variable’s initialized value relates to variable assignment rather than declaration, which comes after the data type has been specified. Declaring a variable as global addresses its scope rather than how to declare the variable itself; it does not change the fundamental requirement of specifying a data type during declaration.