The correct option is C Single Transferable Vote System
Members of the Rajya Sabha are elected according to Single Transferable Vote System and not by direct votes of citizens. Allowing for MLA-based voting, the Rajya Sabha election follows the “system of proportional representation by means of the single transferable vote.”, This basically means that the single vote cast by an MLA is transferable from one candidate to another in two scenarios. One is when a candidate obtains more than what is required for their win and therefore has an unnecessary surplus. The other is when a candidate polls so few votes that they have absolutely no chance. In both the cases, the extra votes are transferred so that there is no wastage.