If the unit price of aluminum is 10 , the slope of the supply curve is closest to:

A. 0.04 .

B. 1.30 .

C. 26.00 .

A producer's supply function is given by the equation:

\[
Q_{s}^{s}=-55+26 P_{s}+1.3 P_{a}
\]

where $Q_s^s$ is the quantity of steel supplied by the market, $P_s$ is the per-unit price of steel, and $P_a$ is the per-unit price of aluminum.