A poll asks residents of a city to report their health status: whether they feel it is excellent, very good, good, or poor, Kenneth uses the results of the poll in a research paper he is writing about the instances of obesity and heart disease in inner cities. Kenneth's professor cautions him about the use of this source. Which reason would the professor MOST likely give for his warning?

A. Peoples view of their own health status may not be entirely accurate

B. The results of this poll might be skewed because of the demographic

C. Cities are different so he shouldnt use just one poll from one city

D. Kenneth’s paper is only supposed to concentrate on physical wellness