10.

Using the results of a Newsweek poll conducted in March of 2009, a 90% confidence interval on the proportion of adult Americans who have a favorable opinion of Barack Obama is given by (0.699, 0.741). If everything else is the same, but the confidence level increases, what happens to the width of the confidence interval?
A)
It decreases.
B)
It increases.
C)
It does not change.

It increases