Option A is the correct answer because it uses the json.dump() method to write the Python dictionary UpdatedConfig into a file named "ifaces.json". The "w" parameter in the open() function means that the file is opened for writing. If the file does not exist, it creates a new one; if it exists, it truncates the file.
The json.dump() function is used to serialize UpdatedConfig (the updated interface configuration) which is a Python dictionary into a JSON formatted string, and then writes it to "ifaces.json" using OutFile.
Finally, OutFile.close() is called to close the file after writing to it.
References: Implementing and Operating Cisco Service Provider Network Core Technologies source documents or study guide