C100DEV CRUD Operations Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  db.shipments.updateMany({ carrier: 'DHL' }, { $pop: { tracking_history: { status: 'cancelled' } } })

  Why it's wrong here

  $pop removes either the first or last element of an array based on a value of -1 or 1, and it does not evaluate a field condition such as status: 'cancelled'. Passing an object to $pop is invalid. It cannot target specific array elements by their contents, so it fails the requirement.

• ✗

  db.shipments.deleteMany({ carrier: 'DHL', 'tracking_history.status': 'cancelled' })

  Why it's wrong here

  deleteMany removes whole documents that match the filter, which would erase any DHL shipment containing at least one cancelled entry. The task explicitly requires keeping documents and removing only the array element. This operation destroys shipment records and is therefore incorrect.

• ✓

  db.shipments.updateMany({ carrier: 'DHL' }, { $pull: { tracking_history: { status: 'cancelled' } } })

  Why this is correct

  The $pull operator removes all array elements matching a condition, so specifying { status: 'cancelled' } strips only those entries from tracking_history. Combining it with updateMany and a carrier filter applies the change to every matching document. This satisfies the requirement to delete array elements without removing documents.

• ✗

  db.shipments.updateMany({ carrier: 'DHL' }, { $unset: { 'tracking_history.status': 'cancelled' } })

  Why it's wrong here

  $unset removes a field entirely rather than an array element, and it does not accept a value condition like 'cancelled'. Using it on tracking_history.status would either delete the status field from every element or fail, leaving cancelled entries present. It cannot selectively remove only the cancelled array elements.