Can someone help explain this? My textbook doesn't explain it very well

2. Here are two types of indexed allocation, what is the difference between these two methods? File allocation table File name Index Hack File allocation table File name Index block File B O 0:00 $0 00:00 O00:00 DKLI DO DDDDDD Start block Length 3030-000 300:0:0:0:0 D0-0-0-0 D0:0:0:0 Fig 3 Fig 4 3. What is Bit Table, how does it work? In your opinion, where shall we store the bit table (main memory or disk)? List your reason. 4. Does different block size impact internal fragmentation, or external fragmentation? Compare the advantages and disadvantages of different block size. 5. What abbreviations FAT and FST stand for? What is the purpose of each of the tables