What can harm crops?
Nematoda influenza vehicles burning chemicals smallpox Roundworms. flooding
A B C D E F G H
Ozone is harmful to humans and crops.
Chemicals can harm crops.
What can harm crops? (A) Nematoda (B) influenza (C) vehicles (D) burning (E) chemicals (F) smallpox (G) Roundworms. (H) flooding