The answer and question are correct. Furthermore, it was suggested that 1800's be changed to 1850's in the question. This could be done, but then it draws away from the focus of the entire paragraph, which is on the 1850's. Just because the answer took place during the 1850's does not mean that it's separate from the 1800's. It happened during the 1800's.
Resin Producing Plants are poisonous for them, not they are poisonous for resin producing plants, as per the passage.