The correct answer <em>is a Terrace</em>.
A farmer living on the edge of a steep mountain that would like to increase the number of crops he can grow, can build a terrace, one Inca advancement that could be of the most use for him.
The region of the Andes is a place where the tallest and difficult to access mountains exist. However, the Incas developed intelligent ways to harvest crops to take advantage of the steepest areas in the high mountains. They built terraces, cisterns and irrigation canals in the form of “s” or snakes in the slopes to angled down around the hills and mountains. The terraces covered thousands of hectares in ancient Peru, where Incas grew potatoes and corn.
This verse means that if there is something in a person's life that causes the person to sin or sway from the will of God, the person should let it go, even if it seems difficult. The difficulty or the pain in letting go of that sin is what is compared to gouging the eye out and throwing it away. It will be very painful to gouge out your eye. So it is better to let go of that sin which is so pleasing, suffer on earth for a short time and enjoy in heaven eternally than to stay in that sin, enjoy on earth for a short time and burn in hell eternally.
Thomas Edison
Reasoning: he applied for the first pattent of the light bulb in 1897
