Final exam contains an invalid answer

I dont recall the question number in the final, but there is a question that asserts as true the statment “–wiredTigerDirectoryForIndexes” allows for putting indexes on another device" (to paraphrase). That statement is in fact false. That option allows for indexes for a database to be located in a sub-directory under the database directory. Per Mongo docs:

When you start mongod with --wiredTigerDirectoryForIndexes , mongod stores indexes and collections in separate subdirectories under the data (i.e. --dbpath ) directory. Specifically, mongod stores the indexes in a subdirectory named index and the collection data in a subdirectory named collection .
That subdirectory can be symlinked to another device but that was not part of the question. Answered a question correctly but missed it because the answer in the test is incorrect.

It’s covered in the course material in chapter 2, specifically in the [Lecture: How Data is Stored on Disk] video right around the 5 minute mark it goes into explaining how using symlinks to store your collections and indexes on different disks can be leveraged to improve IO performance