Graph B does not represent a proportional function. If it were true that $\displaystyle{y}={k}{x}\usepackage{cmbright}\Huge\$ , then k would have to equal 2 since y = 2 when x = 1. However, when x = 0.5, $\displaystyle{2}{x}={2}{\left({0.5}\right)}={1}\usepackage{cmbright}\Huge\$ , which is NOT the y-value corresponding to x = 0.5.