What is commonly used to copy data from a suspect's disk drive?

The correct choice is the image file, which is commonly used to copy data from a suspect's disk drive. An image file is an exact bit-by-bit copy of a storage device, capturing all data on that drive, including deleted files, slack space, and file system structures. This thorough approach makes it invaluable in forensic investigations, as it preserves the integrity and authenticity of the original evidence.

When a forensic investigator creates an image file of a disk drive, they ensure that any analysis or examination of the data is conducted on the copy, thereby avoiding any alterations to the original evidence. This practice is vital for maintaining the chain of custody and ensuring that the integrity of the data is upheld for legal proceedings.

In contrast, backup files are typically used for data recovery and may not capture all aspects of the disk's content, particularly if the backup is incomplete or incremental. Text files, on the other hand, are not suitable for capturing the complete state of a disk drive, as they contain only textual data and not the raw binary data that is essential for digital forensics. Snapshot files are often associated with virtual environments and may capture the state of a system at a particular moment but do not serve the same purpose as a comprehensive disk image.