Answer:
Population A
Explanation:
Usually in statistics, the more we increase the sample size, the more the standard deviation decreases. Similarly, the more we decrease the sample size, the more the standard deviation increases.
Finally, the more the standard deviation or error of Variance the lesser the power to detect an effect.
In this question, Population B has a greater standard deviation and thus would not have as much power as Population A in detecting an effect.
Thus Population A with standard deviation of 2.3 will have highest power to detect an effect.