The correct options are
A Collection of artefacts
C Classification based on their historical date and type
D Preparation of indexes
The process of maintaining material sources of history starts with the collection of artefacts. Later, they are classified according to their historical date and type, and indexes are prepared for easier look through. The collected sources are cleaned with necessary mechanical and chemical processes for preservation. Selected artefacts or their replicas are exhibited and research reports on collected artefacts are published. Selected fossils or their replicas are also exhibited.