Japan, china, and korea were friendly nations who shared culture and customs. rival nations who came into frequent conflict. neighboring countries who shared a common history. countries with very dissimilar culture and customs.

Well, I'm not too sure there is one good answer to this question. 
two options are clearly false: friendly nations who shared culture and customs. and countries with very dissimilar culture and customs.- they do share culture but had way too many conflicts to be called friendly
 
The other two options are both partially true: 
rival nations who came into frequent conflict. - yes, they did come into frequent conflict, but Korea was rarely a rival there, it was rather subdued. But I still think that this is the best answer/ 

neighboring countries who shared a common history. - this could also be argued, depending on what you accept to be neighbouring countries: they Japan is an island and it can share only borders over water, not land with the others- this is also a good answer.

One rather ironic incident involving the economy was with George H.W. Bush, when he campaigned for president in 1988 one of his famous campaign promises echoed across the country was "Read my lips No new taxes". Many said this helped him win the presidency, but later in his term the Democrat controlled Congress passed legislation increasing taxes. Bush tried compromising but in the end he hurt his reputation and taxes did wind up going up, causing quite alot of controversy as a result