Question from the Typescript - Overview test

function reverseArray(arr: any[]): any[] {
 return arr.reverse();
}

function reverseArray(arr: Array<T>): Array<T> {
 return arr.reverse();
}

function reverseArray<T>(arr: T[]): T[] {
 return arr.reverse();
}

function reverseArray<T>(arr) {
 return arr.reverse();
}