What function is used to create a new session variable in PHP?

The function used to create a new session variable in PHP is session_start(). When you call session_start(), PHP checks if a session already exists for the user. If not, it initiates a new session and generates a unique session ID. This enables the use of session variables, which are stored on the server and can persist across different pages and requests.

Once the session has started, you can create and manipulate session variables using the superglobal array $_SESSION. For instance, you can assign a value to a session variable like this: $_SESSION['key'] = 'value'; The session variable now exists and can be accessed throughout the user's session, provided that session_start() is called at the beginning of any script that needs access to session data.

Other options do not exist in PHP’s built-in functions for session management. For example, functions like session_create(), session_new(), and session_variable() are not defined in PHP, making them invalid choices for the purpose of creating a new session variable.