Silk, common currency, fireworks.
Those are the main three I know of.
The correct answer to this open question is the following.
Although there are no options attached, we can say the following.
The above description contrast with early mining operations in the American West in that the formerly conditions of the old west were completely different than the "beautiful hills, waving fields of grass, prancing mule deer, a glimmering lake . . ." description by T.H. Watkins.
Indeed, it was the opposite. American settlers that decided to bet on the west and the "gold fever," found difficult conditions and economic hardships. That was not an easy time and required extra work to find the gold.
And let's have in mind that many people that went to the west were people that have been suffering from the difficult conditions in the Plains during the so-called "Dust Bowl" period in which drought and the lack of rain killed animals and affect the production of crops.
It would be "(D) the bombing of the Oklahoma City Federal Building," that is not associated with Al Qaeda, since this was an act of "domestic terrorism," that was carried out by a Christian white male.
