What does nesting refer to in Java?

Nesting in Java generally refers to the practice of placing one code structure inside another, which often involves the organization of code through indentation, making it more readable. When we consider option B, it specifically mentions "indenting statements inside a block," which aligns well with the concept of nesting.

In Java, blocks of code—like those for classes, methods, loops, or conditional statements—can contain other blocks or structures. For example, you can have a loop inside a method or an if-statement inside a loop. Proper indentation helps to visually convey the hierarchy and relationship between these nested structures, making it easier for developers to read and understand the flow of the program.

Though other options touch on aspects of Java programming, such as loops, global variables, and function calls, they do not encapsulate the specific concept of nesting as described in the question. Indentation is a critical part of illustrating how certain structures are nested within one another, which is why option B is the correct answer when referring to nesting in Java.