The answer is letter B. Particles in the atmosphere clearing the surrounding air which did not occur as a result of oil production and distribution around the Persian Gulf. All other choices such as A, C, D happened or occurred as a result of the oil production around the Persian Gulf.
The correct answer is - 3. maize.
The maize was the basis of the diet of the civilizations of Mesoamerica. It was one of the first wild plants in which the people from this region saw a potential as a big and stable food source, so they started to farm it. All of the civilizations we know from this region, like the Olmecs, Toltecs, Mayans, Aztecs, formed and developed their civilizations around the food source that was provided by the maize.
the picture that shows a plain is 4
GDP, which we use right now, to see how many people have jobs, at what income, to decide how good the economy is. We could possibly use population density, as poorer countries/less developed countries tend to be more dense all around. Mainly economic things though, so GDP, income per capita. We use life expectancy, rate of literacy, freedom index..hope this helps
