What is the role of the `cout` object in C++?

The cout object in C++ is specifically utilized for outputting data to the standard output stream, which is typically the console or terminal window. This functionality is integral to displaying information to users. When you use cout, it enables you to send various types of data—such as strings, integers, or floating-point numbers—directly to the output, enhancing the interactive nature of programs.

For example, when you write a statement like cout << "Hello, World!";, it instructs the program to display "Hello, World!" on the screen. This capability is essential for providing feedback, results, and debugging information during program execution. The usage of the insertion operator (<<) with cout allows for chaining multiple outputs in a single statement, improving code efficiency and readability.

In contrast, the roles of reading input, defining constants, or storing variables are performed by other constructs in C++. Input is typically handled by cin, constants can be defined using const or #define, and variables are created using data types followed by the variable name. Thus, cout specifically serves the unique purpose of facilitating output, making option B the clear choice.