A.
Thus, finding the header of a file means that the first fragment of the file is found, but the other fragments might be scattered anywhere else on the partition, making file carving much more challenging.
By studying how file systems actually do fragmentation and applying statistics, it is possible to make qualified guesses as to which fragments might fit together. These fragments are then put together in various possible permutations and it is tested if the fragments fit together. For some files it is easy for the software to test if they fit, while for others, the software might accidentally fit the pieces together incorrectly.
Pal, T. Sencar and N. Memon, "Detecting File Fragmentation Point Using Sequential Hypothesis Testing - URL now invalid", Digital Investigations, Fall 2008
