When the NLS_DATE_FORMAT is set to DD Mon YYYY, the database expects the date string to be in the format of day, abbreviated month name, and full year.
B . The query SELECT DATE '2019-01-01' FROM DUAL; correctly returns the value 1 Jan 2019 because the ANSI date literal DATE 'YYYY-MM-DD' is independent of the NLS_DATE_FORMAT parameter.
Option A is incorrect because the TO_DATE function requires the format model to match the string literal, which it does not in this case.
Option C is incorrect because TO_CHAR is used to convert a date to a string, not a string to a date.
Option D is incorrect because without specifying that the string is a date, the result is just a string and not a date value.
Option E is incorrect because TO_DATE without a format model relies on the NLS_DATE_FORMAT to interpret the string, and YYYY-MM-DD does not match DD Mon YYYY.