Question 1087703
Determining the margin of error requires a random sample of a population of {{{n}}} and a desired {{{confidence}}} {{{level}}}. 

Assumes a {{{95}}}% level of confidence.

so, you can compute the margin of error {{{(MOE)}}} using this formula:

{{{MOE=t/sqrt(n)}}} where {{{t}}} is a desired {{{confidence}}} {{{level}}} and {{{n}}} is a random sample of a population

{{{MOE=95/sqrt(1000)}}}

{{{MOE}}}= ±{{{3.004163}}}% ...round it

{{{MOE}}}=±{{{3}}}% 




so, your answer is:  

a. ±{{{3}}}%