Answer:
A. True.
Explanation:
To get the standard error of the mean, you need to do the sample standard deviation over the square root of the number of samples, n.
In this case, n = 100. The standard deviation is 12. To get the SAMPLE standard deviation, you do the population standard deviation over the square root of n. That is 12 / sqrt(100) = 12 / 10 = 1.2.
So, to get the standard error: 1.2 / sqrt(100) = 1.2 / 10 = 0.12.
The standard error of the mean is, indeed, 0.12, so the statement is A. True.
Hope this helps!