C. petroleum.
There is a whole wikipedia page dedicated to the petroleum industry of Azerbaijan.
What aspects of Roman government do we still use in our society today?
What styles of Roman architecture and art inspired the European Renaissance?
Was Julius Caesar a Roman hero or villain?
Was it right for Rome to become an empire rather than a republic?
What advancements did the Romans make in science and mathematics?
What advancements did the Romans make in warfare?
How to the Romans compare to the ancient Greeks?
4) African economies became dependent on the sale of cash crops and raw materials.
"<span>The British hoped to tighten control over the empire" would be the best option, but the main reason beyond this was that they wanted to discourage trade with other nations, in order to increase profits. </span>