The correct answer is: D. help organize a program into conceptual units.
A function is a block of code that can be called repeatedly. It has a name and a set of arguments that can be passed to it. The function can then perform some operation and return a value.
Functions are important because they help to organize code into smaller, more manageable units. This makes it easier to read, understand, and debug code. It also makes it easier to reuse code, since functions can be called from multiple places in a program.
Option A is incorrect because functions can be used for more than just giving a name to a block of code. For example, functions can also be used to accept arguments and provide a return value.
Option B is incorrect because functions do not necessarily reduce program size. In fact, functions can sometimes increase program size, because they require additional code to be written to define and call them.
Option C is incorrect because functions do not necessarily accept arguments or provide a return value. For example, a function can be defined to have no arguments and to return no value.
Option E is incorrect because functions are important for organizing code into conceptual units.