How do you declare a JavaScript variable?

Declaring a JavaScript variable involves specifying a name and an optional initial value for that variable. The correct way to declare a variable in JavaScript is by using the keywords var, let, or const.

The keyword var has been used historically in JavaScript and allows for variable declaration with function scope, while let and const provide block-level scope. The keyword let enables you to declare a variable that can be reassigned later, while const is used for variables that should not be reassigned after their initial declaration. This level of control is crucial in modern JavaScript development for managing variables effectively within different scopes.

The other options do not accurately represent how variables are declared in JavaScript. "Declare" is not a keyword in the language; it simply refers to the act of creating a variable. Similarly, "new" is typically used for creating instances of objects, especially when working with constructor functions or classes. "Define" is not a valid keyword for declaring variables either; it's more a concept associated with specifying values or functions rather than declaring variables.