An Accurate Way to Gain Insight into the Public's Perception

An accurate way to gain insight into the public's perception of a candidate is through which of the following?

A) Man-on-the-street opinion polls, because they are conducted by the media
B) Tracking polls, because they are conducted almost daily and enable fine-tuning of the candidate's message
C) Advertising expenditures, because these are indicative of the strongest candidate
D) The primary election, because the response from voters will always indicate the strongest candidate
E) Campaign contributions made by individual households, because this funding  highlights most voters' preference