Which sentence demonstrates correct subject-verb agreement with multiple relative clauses describing the Ambassador's itinerary?

• A. The Ambassador's itinerary, which was classified at the Secret level and which only a handful of staff were privy to, was leaked to the press.
• B. The Ambassador's itinerary, which was classified at the Secret level and which only a handful of staff were privy to, were leaked to the press.
• C. The Ambassador's itinerary, which was classified at the Secret level and which only a handful of staff were privy to, is leaked to the press.
• D. The Ambassador's itinerary, which was classified at the Secret level and which only a handful of staff were privy to, leak to the press.

Answer: (A)