Step 1: Historical context.
The Kingdom of Sardinia was ruled by the House of Savoy. Victor Emmanuel II became the King of Sardinia in 1849 and later the first King of unified Italy in 1861.
Step 2: Analyze options.
(A) Victor Emmanuel: Correct — King of Sardinia, central figure in Italian unification.
(B) Napoleon: French Emperor, not Sardinian King.
(C) Charles X: King of France, not Sardinia.
(D) None of them: Incorrect, since Victor Emmanuel was indeed the king.
Step 3: Conclusion.
The correct answer is (A) Victor Emmanuel.