$\begin{array}{1 1} a.Sterilization \to Hardening \to Selection\; of\; explants \to Inoculation \to Regeneration \to Plantlet \;transfer \\ b. Selection\; of\; explants \to Inoculation \to Regeneration \to sterilization \to Hardening \to Plantlet \;transfer \\ c. Selection \;of\; explants \to sterilization \to Inoculation \to Regeneration \to Hardening \to Plantlet \;transfer \\ d. None\;of\;the\;above \end{array}$