How do you declare a variable in PowerShell?

In PowerShell, variables are declared using the dollar sign ('$') followed by the variable name. This is a fundamental aspect of PowerShell's syntax. The use of the dollar sign signifies that what follows is a variable, allowing the programmer to store and manipulate data within that variable. For example, to declare a variable that stores the value "Hello, World!", you would write $myVariable = "Hello, World!".

This convention is important because it differentiates variables from other types of expressions and commands in PowerShell, ensuring clarity in the code. Understanding this structure is essential for effective scripting and automation in PowerShell, as it forms the foundation for variable manipulation and data handling within scripts.

The other options listed use symbols that do not correspond to variable declaration in PowerShell, which is why they are not applicable or correct in this context.