M201 Chapter2 Multiply Indexes quiz


I think the answer maybe is 4 ,because the _id maybe created

Not may be. An index entry for _id will be created. It will not on the given index name:1,emails:1 but on the index _id:1.

May be the question can be clearer if written as:

When the following document is inserted, how many index entries will be created in the index { name:1 , emails:1 } mentioned above?