You are using a C10 sulfate surfactant for an application at a concentration of 18mM. You are told that it is no longer available and you will have to use C12 surfactant. What is your good estimate of the concentration of the new surfactant for your application? \begin{tabular}{c} 162mM \\ \hline 36mM \\ \hline 54mM \\ \hline 2mM \end{tabular}