Step 1: Constitutional provision.
Article 64 states that the Vice-President of India shall be the {ex-officio Chairman of the Council of States (Rajya Sabha)}.
Step 2: Distinguish other offices.
President is head of state; PM heads the government; Speaker presides over the Lok Sabha, not the Rajya Sabha.
Step 3: Conclude.
\[
\boxed{\text{Vice-President (Option B).}}
\]