Use the Following to Answer Question

Multiple Choice

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 at constant volume.This process is shown in the graph.The specific heat at constant volume of the vapor 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) dividing the rate at which heat is added by the product of the slope of A and the mass of the substance.
D) dividing the rate at which heat is added by the product of the slope of C and the mass of the substance.
E) dividing the rate at which heat is added by the product of the slope of E and the mass of the substance.