A.Two documents will be inserted with _id as 1

B.This will throw a duplicate key error

C.It will insert two documents and throw a warning to the user

D.MongoDB will automatically increment the _id of the second document as 2

A.We cannot change a shard key directly/automatically once it is set up

B.Sharding is enabled at the database level

C.Creating a sharded key automatically creates an index on the collection using that key

D.A sharded environment does not support sorting functionality since the documents lie on various mongod instances

A.specify {all: true} as the third parameter of update command

B.specify {multi : true} as the third parameter of update command

C.updateAII instead of update

D.specify {updateAII: true} as the third parameter of update command

A.Returns 5 comments, beginning with the last 10 items

B.Returns 10 comments, beginning with the first

C.Returns 10 comments, beginning with the last

D.Returns 5 comments, beginning with the first 10 items

A.db.population.aggregate( [{ $group: { _id: { state: Estate", city: "$city" },pop: { $sum: 1 > > >] )

B.db.population.aggregate( [{ $group: { _id: { state: "$state", city: "$city" },pop: { $pop: 1 } } }] )

C.db.population.aggregate( [{ $group: { _id: { city: "$city" },pop: { $sum: "$pop" } } }] )Multi Document Transaction is not supported by MongoDB

D.db.population.aggregate( [{ $group: { _id: { state: Estate", city: "$city" },pop: { $sum: "$pop" } } }] )