The Concentration of a Compound, X, Is Measured at Different

The concentration of a compound, X, is measured at different time intervals during the course of a chemical reaction. After plotting a graph of the concentration of X against time, shown in the graph below, the points labelled A-E on the graph have the following co-ordinates: A: x = 0 seconds; y = 0 mol L^-1
B: x = 8 seconds; y = 0.37 mol L^-1
C: x = 15 seconds; y = 0.49 mol L^-1
D: x = 23 seconds; y = 0.63 mol L^-1
E: x = 30 seconds; y = 0.62 mol L^-1
What is the rate of the chemical reaction after the reaction has been proceeding for fifteen seconds?

A) 3.26 mol L^-1 s^-1
B) 0.017 mol L^-1 s^-1
C) 0.021 mol L^-1 s^-1
D) 57.7 mol L^-1 s^-1
E) 48.39 mol L^-1 s^-1