Which of the following command inside aggregate command is used in MongoDB aggregation to filter the documents to pass only the documents that match the specified condition to the next pipeline stage?

Which is the most suitable advantage of using embedded documents?

Correct syntax for creating an index?

What is Profiler?

Which collections are used by MongoDB to store GridFS data?

Which is correct for _id in MongoDB?

Which call will remove all users who are older than 21 from Users collection?

Which parameter affect ObjectId?

Which is the correct calling of creating an index?

Which option exist in ensureIndex method?

Which is stage of aggregation?