Since there are no digital accounting records for the period covered by the ledger books, they must be retained and stored for at least six years in total. This ensures compliance with the requirement to maintain accounting records for six years, not ten years or three years. Option C is incorrect as firms are not obliged to hold all records in digital formats. While it is sensible to eventually dispose of the ledger books as confidential waste, they cannot be disposed of immediately (making option D incorrect). 

Key Point: The SRA Accounts Rules require that accounting records be retained for at least six years. Even with the adoption of digital records, hard copy records for previous periods must be kept for the required retention period.