The slope of the coexistence curve in a $P$-$T$ diagram for a first-order phase transition is given by the Clausius-Clapeyron equation:
(A)
\frac{dP}{dT} = \frac{L}{T(V_2 - V_1)}
(B)
\frac{dP}{dT} = \frac{TL}{V_2 - V_1}
(C)
\frac{dP}{dT} = \frac{V_2 - V_1}{LT}
(D)
\frac{dP}{dT} = \frac{L}{T^2(V_2 - V_1)}