Which feature is typical of functional programming languages?

Functional programming languages are characterized by their use of higher-order functions, which are functions that can take other functions as arguments or return them as results. This feature facilitates a programming style focused on the application of functions, promoting the idea that functions are first-class citizens in the language. This concept allows developers to write more modular, reusable, and maintainable code, as functions can be composed and manipulated just like any other data type.

Additionally, higher-order functions enable powerful abstractions, such as map, filter, and reduce, which are commonly found in functional programming languages. These constructs allow for operations on data collections without the need for explicit loops, which aligns with the functional programming paradigm that emphasizes immutability and stateless operations.

The other features listed—merging of data and behavior, state management, and use of loops—are more typical of imperative and object-oriented programming paradigms, where state and behavior are indeed intertwined, and loops are commonly used for iteration. In functional programming, however, the focus is on function application and transformation rather than on maintaining state or using loops, thus reinforcing the importance of higher-order functions as a defining characteristic.