Which descriptor defines a low-level programming language?

The correct choice is B, as a low-level programming language is one that is closely related to the architecture of a computer's hardware. It typically provides little abstraction from the machine's instruction set, meaning that programmers have to manage memory and hardware functions directly. This can include languages like assembly language, which uses mnemonic codes to represent machine-level instructions.

Low-level languages allow for fine-tuned control over system resources, making them particularly useful for system programming or applications requiring high performance, such as operating systems and embedded systems. Because of their closeness to hardware, programs written in low-level languages tend to be faster and more efficient than those written in higher-level languages, though they can be more complex and difficult to write and maintain.

In contrast, high-level languages abstract away the details of the hardware, allowing developers to write code that is more readable and easier to maintain. Markup languages, on the other hand, are not programming languages per se, as they are used for structuring data rather than for performing operations. Object-oriented languages are a category of high-level languages that utilize objects to represent data and functionality, facilitating code reusability and organization.