Final answer:
The error that would be thrown if worldedit is not installed or if it isn't the proper version is ImportError.
Step-by-step explanation:
This error will be thrown if worldedit is not installed or if it isn't the proper version.
The correct answer is b. ImportError.
ImportError is raised when a module or package cannot be successfully imported. In this case, if the worldedit module is not installed or if it is not the correct version, an ImportError would be thrown.