To retrieve the Julian date (day number), which DATE command option would be used?

To retrieve the Julian date, which represents the day number within the year, the correct command option to use with the DATE command is +%j. This option formats the output of the date command to display the day of the year as a number ranging from 001 to 366. For example, January 1 would be represented as 001, and December 31 would be represented as 365 (or 366 in a leap year).

The other options serve different purposes: +%V gives you the ISO week number of the year, +%F outputs the date in the format YYYY-MM-DD, and +%Y displays just the year. Hence, only +%j is specifically used to obtain the Julian date, making it the accurate choice for this query.