To understand which statements are true, let's break down the SQL functions and their behaviors in the provided queries. 1. SELECT ROUND(TRUNC(15.193, 1)) FROM DUAL: TRUNC(15.193, 1) truncates the value to a single decimal place, resulting in 15.1. ROUND(15.1) then rounds this truncated value, leaving it as 15. 2. SELECT ROUND(15.193, -1) FROM DUAL: ROUND(15.193, -1) rounds the value to the nearest 10, resulting in 20. 3. SELECT TRUNC(15.193, -1) FROM DUAL: TRUNC(15.193, -1) truncates the value to the nearest 10 without rounding, resulting in 10. 4. SELECT TRUNC(ROUND(15.193, 1)) FROM DUAL: ROUND(15.193, 1) rounds the original value to a single decimal place, resulting in 15.2. TRUNC(15.2) then truncates this value, leaving it as 15. From the above analysis, it's evident that 2 returns the value 20, and 1 and 4 give the same result.