Question

A U.S. government report stated that, “With bank interest rates around
1.0%, 8% of wage earners believe it worthwhile to keep money in a
savings account. However, at 3.0% interest, 36% of wage earners believe
it worthwhile to keep money in a savings account. The margin of error
for both studies is 4 percentage points.”. A proper conclusion from the
studies is that:
A. increasing the interest rate from 1% to 3% will increase the number of
persons saving money in a savings account.
B. increasing the interest rate may well have no effect on the number of
persons saving money in a savings account.
C. increasing the interest rate will increase the number of persons saving
money in a savings account.
D. the interest rate difference between 1% and 3% may well have no effect
on the number of persons saving money in a savings account.

My answer is D, but I'm not sure

Answer 1

Assuming that the margin of 4.0% is for the depositors, at 1.0% depositors = 8 ± 4, while for 3.0%, depositors = 36 ± 4.

Is my assumption valid? If so, I disagree.