Which of the following programming languages is considered dynamically typed?

The correct choice, PHP, is considered a dynamically typed programming language because variable types are determined at runtime rather than at compile time. This means programmers do not need to explicitly declare the type of a variable when it is created, allowing for greater flexibility in coding. In PHP, a variable can hold different types of data throughout its lifespan, and the type can change based on the value assigned to it.

In contrast, the other languages listed have different typing systems. C++ and C# are statically typed, meaning that the variable type must be explicitly defined before it can be used, and this type cannot change during its lifetime. Swift, while offering some dynamic capabilities, is primarily a statically typed language, requiring variable types to be known at compile time, thus falling outside the definition of dynamically typed languages.