A student's grade point average (GPA) is a numerical representation that typically includes a decimal to account for the precision of the average (e.g., 3.75). Therefore, it should be declared as a floating-point data type to accommodate the decimal part. Since a student's GPA can change over time with the addition of new grades, it should be declared as a variable rather than a constant.
References:
* The concept of using floating-point variables for numerical data that includes decimals is a standard practice in programming. This is discussed in programming resources such as "Programming: Principles and Practice Using C++" by Bjarne Stroustrup, which explains data types and their uses. Additionally, the concept of variables and constants is covered in "The C Programming Language" by Brian W.
Kernighan and Dennis M. Ritchie.

A programming library is a collection of pre-written code that developers can use to optimize tasks and improve productivity. Here's why the selected statements are correct:
* A: Libraries must be included or imported into your program before you can use the functions or objects they contain. This is because the program needs to know where to find the code it's executing12.
* B: A library typically includes multiple functions, objects, or classes that are related to a specific task or area of functionality. This allows developers to reuse code efficiently12.
* D: By providing pre-written code, libraries save developers time and effort, which in turn improves their productivity. Instead of writing code from scratch, developers can focus on the unique aspects of their project12.
The other options are incorrect because:
* C: While it's true that poorly designed libraries can affect performance, well-designed libraries can actually make programs more efficient by providing optimized code.
* E: A single program can include multiple libraries as needed. There's no limit to the number of libraries a program can use.
* F: Libraries often contain multiple functions and variables, not just one function.
References:
* CareerFoundry's guide on what a programming library is1.
* Codingem's complete guide on libraries in programming2.