Which of the following are common uses of the json_encode() and json_decode() functions in PHP?

The json_encode() and json_decode() functions in PHP have multiple common uses. They are used for serializing PHP data into a JSON string, deserializing a JSON string into PHP data, and interchanging data between PHP and JavaScript applications. The correct option is "All of the above" as all the mentioned uses are valid and common. For more details, refer to the PHP documentation on json_encode(): http://php.net/manual/en/function.json-encode.php and json_decode(): http://php.net/manual/en/function.json-decode.php