According to the Text, What Has Been an Important Concern

According to the text, what has been an important concern about target marketing among gaming officials and business owners in Colorado?

A) Their target market relies too heavily on "high rollers," which are decreasing in number.
B) Their target market relies too heavily on the lower income population
C) Their heavy reliance on the Native American casino market, which is 95% of the market base.
D) Their heavy reliance on the Denver metropolitan market, which is 95% of the market base.
E) None of the above