By how many times does the sample size have to be increased to decrease the margin of error by a factor of 1/7?

The sample size must be increased by a factor of ___?__ to decrease the margin of error by a factor of 1/7. 

What is the general relationship, if any, between the sample size and the margin of error?

MULTIPLE CHOICE

A. Increasing the sample size by a factor M results in the margin of error decreasing by a factor of 1/M.

B. Increasing the sample size by a factor M results in the margin of error decreasing by a factor of 1/M².

C. Increasing the sample size by a factor M results in the margin of error decreasing by a factor of 1/ square root M

D. There is no relationship between the sample size and the margin of error.