How can an application property value be retrieved through script?

The correct method for retrieving an application property value through script is GlideApplicationProperty.getValue('lookup.value').

This approach leverages the GlideApplicationProperty class, which is specifically designed to manage and access application properties within the ServiceNow platform. The method getValue() is invoked with the name of the property as an argument, in this case, 'lookup.value'. This method effectively returns the corresponding value stored for that property, enabling developers to access configuration values directly within their scripts.

In the context of ServiceNow, using the GlideApplicationProperty object ensures that the script adheres to the recommended practices for accessing application properties. It helps avoid potential issues related to performance and compatibility when interacting with system properties in different environments.

In contrast, the other options may not align with the accepted methods for accessing application properties in ServiceNow. Each of them either references the incorrect class or uses a method that is not recognized for retrieving property values, making them less suitable for the intended purpose.