If you construct a 90% confidence interval for the population proportion and a 95% confidence interval for the population proportion, the 95% confidence will have a wider interval. This is because a higher confidence interval will provide more possible values from which the true value will be determined. Therefore, If you want more confidence that an interval contains the true parameter, then the intervals will be wider.
C. You'd be starting at a higher floor (positive number) and descending floors (negative number per x). If you assume x is time it's a little more logical and visual.
