Under the Articles of Confederation, the years

between 1781 and 1787 are often referred to as

the "critical period" because the

(1) colonies were forced to pay high reparations

to England

(2) states were fighting the French and Indian

War

(3) southern states threatened to secede from the

Union over the issue of slavery

(4) central government lacked the power to deal

with major problems

Option (3) southern states threatened to secede from the Union over the issue of slavery

Explanation:

By the 18th century, the United States faced a number of issues. For example, the slave trade was one of the issues that resulted in the state being brought into turmoil. This was because the United States was already divided into two - the Northern region and the Southern region. The Northern region was the one region that still held to slave trade despite it being abolished. The South, offered slaves freedom. Thus, the movement of he slaves from the North to the South was a major issue. Thus, the war was over the trade as the north though it was suffering due to the decrease in slave labor.

1. the question asks the most appropriate, which seems to rule out "all of the above." your choice appears to be the correct one.

2. the protocol described is good for identifying correlation, but not cause and effect. for cause/effect, you need to devise a protocol that will assign the treatment (or not) to groups that have essentially the same "demographics" with respect to all the other variables. your choice regarding control group seems appropriate. random assignment of treatment (choice d) may be appropriate also. (i think you can argue that b and d are just different descriptions of the same method.)

3. d will randomize the birds, but may not guarantee there are 10 in each group. e will do both, so seems the better choice.

comment on question 2

based on the problem statement, it seems clear that confident, attentive drivers are more likely to use daytime running lights. so, the protocol might need to be devised in such a way that the lights would be turned on or off without the driver's knowledge. (an attentive driver will figure it out.) assigning a confident, attentive driver to a group required to drive without running lights might mess with his/her confidence and attentiveness. you don't want your experiment to do that. (nor do you want the experiment to subject a driver to greater risk of accident as a consequence of driving without running lights.) experiments involving human safety are always problematic.