Choose the correct answer below:

a. increasing the sample size by a factor of 4 increases the standard error by a factor of 2. changing the standard error doubles the magnitude of the standardized z-value.

b. increasing the sample size by a factor of 4 decreases the standard error by a factor of 2. changing the standard error doubles the magnitude of the standardized z-value.

c. increasing the sample size by a factor of 4 decreases the standard error by a factor of 2. changing the standard error decreases the standardized z-value to half of its original value.

d. increasing the sample size by a factor of 4 increases the standard error by a factor of 2. changing the standard error decreases the standardized z-value to half of its original value.