Answer:
B. Larger sample size and lower confidence level
Step-by-step explanation:
The margin of error of a confidence interval is given by the following formula:
In which is the standard deviation of the population and n is the size of the sample.
z is related to the confidence level. The higher the confidence level, the higher the value of Z.
So, the margin of error is direct proportion to the confidence level and inverse proportional to the sample size.
We want to decrease the margin of error.
So the correct answer is:
B. Larger sample size and lower confidence level