C. Because the pink rectangle is a plane like a piece of flat paper, and you look at the points that are sitting on the plane which are points C and E
Substinence farming is farming food that is just enough to live off of. You don't sell substinence crops.
Commercial farming is growing food to sustain you, and having enough left over to sell.
In both, you grow food and you keep some (or all) for yourself.
<span>True, however 50% is rather optimistic value, it's probobally more. The main source of water is in the ground and the groundwater gets constantly more contaminated with road salt, oil, gasoline and other chemicals (and as you can see, these are all manmade products).</span>
There are many ways to determine what minerals are present in a sample. You can observe its color, streak, luster, magnetism, cleavage and hardness. Obviously, you can see what color it is and whether it is metallic or cloudy, but other tests may be required. Streak is tested by rubbing the mineral onto a streak slab of concrete to see what color the powder is. Magnetism is determined by putting a magnet next to the sample, or placing it next to a dish of iron filings. Cleavage is determined by cracking the sample to see the way it fractures. Finally, to determine hardness, you scratch test rocks with the sample, like as controls. I hope this answered your question. (Also, questions like this would best fit under chemistry, because geography is the study of political land)
Do you mean the outcome of the structures or natural formations nearby or do you mean the effect on the wind itself like would it deprecate after a while?