I am pretty shore the answer is A
They gave us the written word where before stories were word of mouth. Even though they wrote in Latin many of the root words are used today in the English language. The gave us measurements like mile, foot and inche. Also Roman numerals are still used, especially in regards to time-pieces. They gave us Christianity. They also introduced some spices and small animals like poultry.
Walden is Thoreau's account of two years he spent living in a small cabin he built next to Walden Pond in Concord, Massachusetts.
This statement best describe and summarize the third paragraph of economy in walden
hope it helps