Which of these is not a programming language

A programming language is a formal set of instructions and syntax rules used to write logic that a computer can execute, such as performing calculations, making decisions, or controlling hardware. Java and C++ are both classic examples: they support variables, loops, conditional statements, and functions, and code written in them is compiled or interpreted into machine instructions.

HTML (HyperText Markup Language) is used to structure content on web pages using tags, and while it is sometimes loosely called a "language," it does not contain logic, loops, or conditions, so it is technically a markup language rather than a programming language.

iOS, however, is not a language at all. It is a mobile operating system developed by Apple that manages the hardware and software resources of iPhones and iPads, similar in role to Android or Windows. An operating system runs and manages programs; it is not itself a set of syntax rules for writing programs.

Because the question asks which option is not a programming language, and iOS is fundamentally an operating system rather than any kind of language, it is the correct choice.

Exam tip: when a list mixes operating systems, markup languages, and true programming languages, first separate out anything that manages devices or displays content rather than expressing computational logic.