In an election poll, 200 people were surveyed and 45% expressed their likelihood to vote for a particular candidate. the margin of error on this estimated support is closest to

A margin of error is an amount (usually small) that is allowed for in case of miscalculation or change of circumstances. A general approach for finding a margin of error involves using the standard deviation of a sample proportion. 

Roughly 95% of all normally distributed data fall within two standard deviations of the mean. So the margin of error is two times the  standard deviation (SD)
margin of error = 2*SD
SD=sqrt(p*(1-p)/n)
p is probability of the event and n is the sample size.
In our case, p=0.45 and n=200.
SD=sqrt(0.45*0.55/200)=sqrt(0.001)-0.03

The answer would be holiday inn.