Answer:
Option D.
Step-by-step explanation:
Recall that the wider the confidence interval, the greater the variability.
In other words, wider confidence interval will have bigger sample standard deviation.
For option A, the width is |48-42|=6
For option B, the width is |50-40|=10
For option C, the width is |55-35|=20
For option D, the width is |45.5-44.5|=1
Therefore the team in option D has the smallest sample standard deviation.
As for the confidence level, it is just telling us the extent to which we confidence that, the parameter is within the interval
