Radium was discovered by Maria Sklodowska-Curie -the correct answer is b. Actually she discovered it together with her Husband, Pierre Curie, they obtained it from a uranite sample.
Strangely enough the correct answer here would be actually D as the voting ballots before the 1890s were in fact printed by the political parties themselves. Today the printing of ballots is a very serious business and there are strict regulations and control mechanisms in place in order to stop voter fraud which unfortunately is a big issue.
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A national border would most likely have the most protection because nation's seek to prevent the import of illegal goods, movement of individuals into the country, and also to protect their borders against potential foreign invasion. Traditionally national borders would have more defenses, army, security forces, and police to protect the border than any of the rest of these borders.
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After the Royal Japanese marines attacks on Pearl Harbor The US citizens felt panic, especially the West Coast resident, so reprisals were taken against the Japanese who lived in the western part of the country, in the states of California, Arizona, Oregon and Washington.
Concentration camps for Japanese in the United States accommodated some 120,000 people, mostly ethnic Japanese, more than half of whom were American and Japanese citizens from Latin America, mainly from Brazil and Peru, who were deported under pressure from the US government, in establishments designed for that purpose in the interior of the country, during 1942 and 1948.
The objective was to move them from their habitual residence, mostly on the west coast, to facilities built under extreme security measures. The fields were closed with barbed wire, guarded by armed guards, and located in places far from any population center. Attempts to leave the camp sometimes resulted in the dejection of the inmates.
For all of the above, American citizens of Japanese origin felt like prisoners of war, hostages of a situation they did not choose and in which they did not act.