It’s C, mostly by process of elimination.
A is instantly discardable because American dollar bills are not metal.
B is discardable because the opposite is true. Money must be available in limited amounts because scarcity is what gives currency value.
D is instantly discardable because not all countries use the same currency. A US dollar is not a Euro.
C is correct because money must be easily transferable, or it cannot be easily spent. If you cannot spend/use/transfer a currency, it has no value.
"Exploded", because more people wanted to get work in factories, etc.. and they thought it was a better to work in industries then farming.
conditions were poor in most cases, and that led to the creation of unions in most cases.
The answer to your question is area = 259.81
I give you a clue the answer is between 2)Halley's comet and 4)Polaris.