Which of the following defines data types?

Data types are fundamental concepts in programming that specify the kinds of data a variable can hold. Each data type determines what kind of values a variable can store, such as integers, floating-point numbers, characters, or even more complex structures like lists or objects. Understanding data types is crucial for effective programming as it affects how data can be manipulated, how much memory is allocated, and what operations can be performed on the data.

For instance, when defining a variable to hold a number, declaring it as an integer data type restricts it to whole numbers, while a floating-point data type allows for decimal values. This distinction is essential for both operations within the program and for ensuring that the program runs efficiently and correctly. Thus, the correct answer emphasizes this core concept of data representation in programming.