A reaction is taking place at a constant tempurature and pressure in a series of reactors, the Levenspiel plot for this reaction on the right.

a$.)$ Select a series of reactors $($CSTRs and PFRs$)$ and design a sequence to minimize the total volume to achieve $100\%$ conversion with the Levenspiel plot. Please shade the area for each reactor you choose on the plot directly.

b$.)$ Determine the volume for each reactor in your series based on the values from the figure.