Given the Average Outcomes for the Treated and Control Groups

Multiple Choice

Given the average outcomes for the treated and control groups, and their respective sample standard deviations, how does the number of observations impact the spread of a confidence interval?

A) Only increasing the number of treated will decrease the spread of the confidence interval
B) Only increasing the number of control groups will decrease the spread of the confidence interval
C) Only increasing the number of treated will increase the spread of the confidence interval
D) None of the answers is correct.