When should one should avoid embedding one document within another in MongoDB?

Point out the correct statement.

Which is a valid MongoDB document?

Choose the statement that best describes the query below: db.myCol.find().sort({_id:1});

Suppose we have a collection of users with different ages. Which call will find the oldest person with the name John?

Describe the best use case for choosing MongoDB map-reduce.

Which aggregation option is used to specify the fields that need to be passed to the next stage of the aggregation pipeline?

Best describes the concept of Replication in MongoDB ?

Regarding indexing and performance in MongoDB, choose the correct statement :

In MongoDB, a query ____ consists of a combination of query, sort, and projection specifications.

What is a covered query?