Many people think that a national lobby's successful fight against gun control legislation is reflecting the will of a minority of Americans.

Many people think that a national lobby's successful fight against gun control legislation is reflecting the will of a minority of Americans. A previous random sample of 4000 citizens yeilded 2250 who are in favor of gun control legislation. How many citizens would need to be sampled if a 90% confidence intervals was desired to estimate the true proprotion to within 5%?
a. 267
b. 249
c. 271
d. 282