Multiple factors were involved in the decision of exploration of Mars.
Mars is similar to Earth in size and it is the next planet. Moreover, evidence was present to suggest that liquid water existed, and may possibly still exist, on Mars. All of these factors led to the planet's exploration.
They mostly grew wheat, barley, oats, rye, and corn. because of this, they were basically known as the "Breadbasket". So I believe your answer would most likely be wheat.
For the answer to the question above.
The best answer I can give is letter B.
During the civil war, there was also a competition in the global market on the supply of cotton so Europe sought other suppliers from India and Egypt and this is why the price is down after 1865
Immigration would be the best option
the answer is A. at first the cotton gin was supposed to make things easier for slaves. but with the cotton gin, cotton became more and more wanted which made the need of slaves raise.
