It's B
Kilograms literally means Thousand grams..
So, 7.2 thousand grams -- 7,200 grams
As far as a threat, North Korea has been seen as such for many years (since WWII), when North Korea sided with Russia. America and its Capitalism were not fond of the Communist party, and so we have really been fighting/being concerned about Russian influence.
Historically North and South Korea have been in conflict many years before America and Russia got involved. When we did though it got worse.
Trump has done very little to resolve this, some would say he is making it worse.
AND as for any current events ask Google!
A biggie: the transcontinental railroad. Because it would economically improve wherever it was, both the North and the South competed for the railroad to be in their respective territory, evidenced by the Kansas-Nebraska Act and the Gadsen Purchase and induction of California as a free state in 1860.
In addition: people could get land cheap because it was abundant and might leave to start afresh economically.
There's other stuff I can't remember as clearly, but there's a little and I hope it helps :)
B) Granite is an igneous rock.
