In which of the following conditions, the root can be left in the alveolar process?
Conditions for a root to be left in the alveolar process:

The root fragment must be small, usually no more than 4 to 5mm in length.
The root must be deeply embedded in bone.
The tooth involved must not be infected, and there must be no radiolucency around the apex.
When the risk is too great, if removal of the root will cause excessive destruction of surrounding tissue or damages important structures like inferior alveolar nerve or the root is pushed into tissue spaces or maxillary sinus.
Small root fragment, if size is 4-5 mm in length
The root must be deeply embedded in bone
The tooth involved must not be infected, and there must be no radiolucency around the apex.
All of the above