Alice and Bob are both users on a Unix system, and Alice wants to share some files in a work documents directory with Bob. Alice executes the following series of commands: [alice@research home]$ pwd /home [alice@research home]$ ls -ld alice 3 alice [alice@research home]$ cd [alice@research alice]$ ls -ld work-docs/ drwxr-x--- alice 4096 Apr 29 10:43 alice drwxrwx--- 2 alice alice 4096 Apr 29 10:43 vork-docs/ [alice@research alice)$ cd work-docs/ [alice@research work-docs]$ 1s -1 total 8 1 alice 1 alice -rw-rw-r- alice 49 Apr 29 10: 40 file1. txt 22 Apr 29 10:43 file2. txt -rw-rw-r-- alice [alice@research work-docs]$ chmod 644 file2.txt [alice@research work-docs]$ umask 0002 [alice@research work-docs]$ vi file3. txt [alice@research work-docs]$ (In the final command, she uses the vi editor to create a third document). Bob subsequently executes the following commands: [boboresearch bob]$ id uid-1004 (bob) gid=1004 (bob) groups-1004 (bob),1003 (alice) [bob@research bob]$ cd "alice/vork-docs a. (1 mark) Will the ed "alice/work-docs command issued by Bob succeed? b. (3 marks) Can Bob edit the file file1.txt? If not, can he overwrite it, and why? c. (3 marks) Can Bob edit the file file2.txt? If not, can he overwrite it, and why? d. (3 marks) Can Bob edit the file file3. txt? If not, can he overwrite it, and why?