Which of the following correctly creates a function that doubles a number using an arrow function expression?
The correct way to create a function that doubles a number using an arrow function expression is `const double = n => n * 2;`. This is a concise arrow function that takes a single parameter `n` and implicitly returns the result of `n * 2`. Arrow functions were introduced in ES6 and offer a more compact syntax for function expressions. When an arrow function has a single parameter, the parentheses around the parameter list are optional. When the function body consists of a single expression, the curly braces and `return` keyword can be omitted, and the expression's result is implicitly returned. This makes arrow functions particularly elegant for short, simple operations. Option 1 is also valid but less concise because it explicitly uses a return statement. Option 3 is missing a return statement (so it would return undefined). Option 4 is invalid syntax that mixes function declaration and arrow function syntax.