A. $4$A. $4$ B. $12$ C. $\displaystyle \frac{1}{4}$ D. $3$ E. $1$

1. When a line passes through the origin, $\left(0, \; 0\right)$, the line represents a proportional relationship between $x$ and $y$. The unit rate is $r$ when the line passes through $\left(1, \; r\right)$. Because the point $\left(3, \; 12\right)$ is on the graph, the point $\displaystyle \left(1, \; \frac{12}{3}\right) = \left(1, \; 4\right)$ is also on the graph. Therefore, the unit rate is $4$. No More Steps