Random Array Element in PHP

Задание 1

Given an array:

php<?php
  $arr = ['a' => 1, 'b' => 2, 'c' => 3];
?>

Display a random key from this array.

Задание 2

Given an array:

php<?php
  $arr = ['a' => 1, 'b' => 2, 'c' => 3];
?>

Display a random element of this array.