请教XDJM两道逻辑题（1）

liflyy

3. during the nineteenth century, Britain's urban population increased as its rural population diminished. a historian theorizes that, rather tan industrialization's being the cause, this change resulted from a series of migrations tu urban areas, each occasioned by a depression in the agrarian economy. to test this hypothesis, the historian will compare economic data with population census data.
Q: support
A: (a) the periods of greatest growth in the industrial economy were associated with a relatively rapid decline in the rural populations.  
   (b) the periods of greatest strength in the agrarian economy were associated with relatively slow growth in the urban pupolation.
为什么是B而不是A。B是不是推得太远了。

4。according ti a 1980 survey, ten percent of all United States citizens over the age of sixteen are funtionally illiterate. therefore, if the projection that there will be 250 million uninted states citizens over sixteen in the year 2000 is correct, we project that 25 million of there citizens will be funtionall iliterate
Q: weaken
A: (a) from 1975 to 1980 there was a three-percent decrease in the rate of funtional illteracy among united states citizens over the age of sixteen.
   (b) many united States citizens included in the 1980 survey would also be included in a survey conducted in the year 2000.
why a not b

5.senator: jones is highly qualified for appointment as a judge, as evidenced by jones's receiving a unanimous vote of "qualified" on the formal rating scale used by the lawyers'
committee. that committee advises the senate on judicial appointments.
Q: best reason for dismissing the senator's claim that jones is highly qualified?
A: (a) several members of the lawyers' committee are not themselves qualified for judicial appointment.
   (b) the lawyers' committee gives a unanimous vote of either "highly qualified" or "very highly qualified" to 95 percent of all candidates for judicial appointments.
why b not a