Question

Which are human systems?
a the Amazon Rain Forest
I the Appalachian Trail
the George Washington Bridge
the Himalayas
the Hoover Dam
the North American Free Trade Agreement
the San Andreas Fault
the Suez Canal

Answer 1

Answer:

it will be anything that is not made by nature, but by men. forests are not, mountains as well. not the fault either

Answer 2

George Washington bridge, Hoover dam, north American free trade agreement, and Suez canal are man made. Rest are natural