When you use the INTERVAL literal for months, the result is displayed in years and months if the total number of months exceeds 12.
In the query given:
SELECT INTERVAL '100' MONTH DURATION FROM DUAL;
the output will display the interval of 100 months converted to years and the remaining months. 100 months is equal to 8 years and 4 months. Hence, the correct answer is:
DURATION +08-04