Answer: Third investment is the least simple interest and Second investment is the most earned simple interest.
Explanation:
Since we have given that
Investment of $3,000 at 5% simple interest for 20 years .
Simple interest would be

Investment of $1,000 at 16% simple interest for 20 years
Simple interest would be

Investment of $3,000 at 16% simple interest for 2 years.
Simple interest would be

Hence, Third investment is the least simple interest and Second investment is the most earned simple interest.