Both because you need both farm and and transportation
A. i think is the best answer
Kievan Russia grew from the trade cities founded by Swedish Varangians. Kiev became the dominant city under Vladimir I, whose conversion to Orthodox Christianity and marriage to a Byzantine princess oriented Kiev toward Byzantium. Kiev thus became a bulwark against the spread of Latin Christianity.
Answer:
Humans cause change in the environment as there is overwhelming evidence that human activities, especially burning fossil fuels, are leading to increased levels of carbon dioxide and other greenhouse gases in the atmosphere, which in turn amplify the natural greenhouse effect, causing the temperature of the Earth's atmosphere, ocean, and land surface to increase. That greenhouse gases "trap" infrared heat is well established through laboratory experiments going back to 1856 when Eunice Foote first measured the effect.The well-documented trend of increasing of CO2 in the atmosphere is caused by the burning of fossil fuels and massive land cover changes. The "smoking gun" that shows clearly that human activities are responsible for recent increases in carbon dioxide in the atmosphere is provided by carbon isotopes (carbon atoms of different atomic weight). These isotopes allow scientists to "fingerprint" the source of the carbon dioxide molecules, which reveal that the increased CO2 in the atmosphere is caused by fossil fuel burning also.
