Marshall's mistake lies in his conclusion about the growth rates of the two functions. The correct response is:
Marshall is only considering a small portion of the domains of the functions. If he went farther to the right on the graph, he would observe that the growth rate of f(x)=6⋅1.5^x eventually surpasses the growth rate of g(x)=5x+10 for large values of x.
This choice emphasizes that the exponential function \( f(x) = 6 \cdot 1.5^x \) will grow at a faster rate than the linear function \( g(x) = 5x + 10 \) as \( x \) increases significantly, thus illustrating Marshall's error in judging the growth rates based on limited information.