Which of the Following Pairs of Equations Describes the Supply

Multiple Choice

Which of the following pairs of equations describes the supply and demand curves given in the accompanying demand and supply tables? $$\begin{array} { | c | c | c | } \hline \text { Price } & \text { Quantity Supplied } & \text { Quantity Demanded } \\\hline \$ 20 & 0 & 40 \\\hline \$ 25 & 10 & 40 \\\hline \$ 30 & 20 & 40 \\\hline \$ 35 & 30 & 40 \\\hline \$ 40 & 40 & 40 \\\hline \$ 45 & 50 & 40 \\\hline\end{array}$$

A) Qs = P - 40; Qd = 40P, respectively
B) Qs = P - 20; Qd = 40, respectively
C) Qs = 2P - 40; Qd = 40, respectively
D) cannot be determined