The command userdel --force --remove bob is used to delete the user account named bob and all its associated files. The --force option forces the removal of the user account, even if the user is still logged in. The --remove option forces userdel to remove the user's home directory and mail spool, even if another user uses the same home directory or if the mail spool is not owned by the specified user12. Therefore, options A and B are true regarding this command.
The other options are not true because:
* Option C is false because the locate database is not updated by the userdel command. The locate database is updated by the updatedb command, which is usually run by cron as a scheduled job3.
* Option D is false because the userdel command does not remove all files owned by bob from all mounted filesystems. The userdel command only removes the user's home directory and mail spool, and it does not search for and delete the user files located in other file systems. You have to search for and delete the files manually1.
* Option E is false because the userdel command does not delete the group with the same name as the user, unless the USERGROUPS_ENAB parameter is set to yes in the /etc/login.defs file and the group has no other members14.
References:
* How to Delete/Remove Users in Linux (userdel Command) | Linuxize
* userdel(8) - Linux manual page
* updatedb(8) - Linux manual page
* Understanding the /etc/login.defs File | Linuxize

The correct crontab entry to execute the script chklog three times per month between 3 p.m. and 5 p.m. is:
3 15,16,17 * * * chklog
The crontab entry has five fields that specify the time and frequency of the job, followed by the command or script to be executed. The fields are:
Minute: the minute of the hour when the job should run, from 0 to 59
Hour: the hour of the day when the job should run, from 0 to 23 (in 24-hour format) Day of month: the day of the month when the job should run, from 1 to 31 Month: the month of the year when the job should run, from 1 to 12 Day of week: the day of the week when the job should run, from 0 to 6 (where 0 and 7 are Sunday) The asterisk (*) means any value, and the comma (,) means a list of values. Therefore, the crontab entry above means:
Run the job at the 3rd minute of the hour
Run the job at the 15th, 16th, and 17th hour of the day (which are 3 p.m., 4 p.m., and 5 p.m.) Run the job on any day of the month Run the job on any month of the year Run the job on any day of the week This will execute the script chklog three times per day, every day of the month, and every month of the year, which is equivalent to three times per month.
The other options are incorrect because:
A . This will run the job at any minute of the hour, but only at the 3rd, 4th, and 5th hour of the day (which are 3 a.m., 4 a.m., and 5 a.m.), and only on the 1st day of the month.
B . This will run the job at the 3rd minute of the hour, but only at the 3rd, 4th, and 5th hour of the day (which are 3 a.m., 4 a.m., and 5 a.m.), and only on the 1st day of the month.
D . This will run the job at the 0th minute of the hour (which is the top of the hour), but only at the 15th, 16th, and 17th hour of the day (which are 3 p.m., 4 p.m., and 5 p.m.), and only on the 1st day of the month.
E . This will run the job at any minute of the hour, but only at the 15th, 16th, and 17th hour of the day (which are 3 p.m., 4 p.m., and 5 p.m.), and only on the 1st day of the month.
Reference:
Crontab Explained in Linux [With Examples]
'crontab' in Linux with Examples - GeeksforGeeks
Linux Crontab Command Help and Examples - Computer Hope
Crontab in Linux with 20 Useful Examples to Schedule Jobs - TecAdmin
Linux crontab tutorial with Examples - Linux Tutorials - Learn Linux ...

The correct syntax for selecting specific columns from a table in SQL is to use the SELECT keyword followed by a comma-separated list of column names and then the FROM keyword followed by the table name. Therefore, the only option that follows this syntax is C. SELECT name, address FROM contacts; The other options are incorrect because they either use parentheses around the column names, which are not needed, or they omit the comma between the column names, which causes a syntax error. Reference: https://www.sqltutorial.org/sql-select/
https://www.w3schools.com/mysql/mysql_select.asp