Answer:
the answer is (c) the US Census Bureau
Answer:
<u>Mould board plough, disc plough, soil stirring plough, ridger plough,</u> tool frames/carriers with mouldboard plough or tillage sweeps, etc. are improved implements designed for breaking soil. Ploughs are used to break soil and invert furrow slice to control weeds, etc.
Like, where 4 canyons are located at? Alright then...
Grand Canyon - Arizona
Palo Duro Canyon - Texas
Bryce Canyon - Utah
Three Gorges - China