Place mercury in the reactor. After a large amount of work, only a tiny portion of gold is created.
Decontaminate the resulting gold. This is harder than it sounds because you can't separate out non-radioactive gold from radioactive gold using purely chemical methods.
It should be obvious from this process that it currently costs much more money to create non-radioactive gold than you could ever earn by selling the gold. Creating gold from other elements is currently an expensive laboratory experiment and not a viable commercial activity. Perhaps technology will improve enough in the future to make creation of gold in nuclear reactors a profitable economic enterprise.
A blue shift is any decrease in wavelength, with a corresponding increase in frequency, of an electromagnetic wave; the opposite effect is referred to as red shift. In visible light, this shifts the color from the red end of the spectrum to the blue end.
Seamount and guyot are types of mountain - so we can reject those options, since we're looking for a flat surface, not a mountain.
A trench is a narrow ditch, or depression so also it's not a plain
The correct answer is abyssal plain - it's a plain typically next to a continental rise (leading to the continent) and a mid-ocean ridge.
