Use the Following to Answer Question

Use the following to answer question:
-Heat is added to a substance at a constant rate.The substance starts as a solid and is melted; the liquid is heated and vaporized; finally,the vapor is heated.This process is shown in the graph.The latent heat of vaporization can be found by

A) multiplying the length of B (in seconds) by the rate at which heat is added,and dividing by the mass of the substance.
B) multiplying the length of D (in seconds) by the rate at which heat is added,and dividing by the mass of the substance.
C) multiplying the slope of A by the rate at which heat is added,and dividing by the mass of the substance.
D) multiplying the slope of C by the rate at which heat is added,and dividing by the mass of the substance.
E) multiplying the slope of E by the rate at which heat is added,and dividing by the mass of the substance.