根据下面资料，回答题
German Prime Minister Otto Von Bismarck may be most famous for his 11 and diplomatic talent, but his contributions to the society include many of today′s social insurance programs. During the middle of the 19th century, Germany, along with other European nations, 12 an unusual outbreak of workplace deaths and accidents as a result of growing 13 . Motivated in part by Christian sympathy for the helpless as well as a practical political impulse to get the created of the socialist labor movement, Bismarck 14 the world′ s first worker′ s compensation law in 1884.
By 1908, the United States was the 15 industrial nation in the world that lacked workers′ compensation insurance. American′s injured workers could seek compensation in a court of law, but they still faced a number of tough legal barriers. 16 , employees had to prove that their injuries directly 17 employer′s lack of care and they themselves were ignorant about potential danger in the workplace. The first state workers′ compensation law in this country passed in 1911, and the program soon 18 throughout the nation.
After World War II, benefit payments to American workers did not 19 the cost of living. In fact, real benefit levels were lower in the 1970s than they were in the 1940s, and in most states the maximum benefit was below the poverty level for a family of four. In 1970, President Richard Nixon set up a national commission to study the problems of workers′ compensation. Two years later, the commission issued 19 key recommendations, 20 one that called for increasing compensation benefit levels to 100 percent of the states′ average weekly wages.
A.experimented
B.explored
C.experienced
D.excluded