The correct option is B Victor Emmanuel II, the ruler of Sardinia-Piedmont, was the mastermind to the plan for united Italy.
Revolutionaries like Guiseppo Mazzini failed in their attempt to unite Italy. The mastermind of the plan for united Italy was Count Camillo de Cavour, the Chief Minister of Sardinia-Piedmont. He along with Victor Emmanuel II took the initiative. In alliance with the French, they first defeated the Austrian Habsburgs to free Northern Italy. Thereafter, revolutionaries like Garibaldi and the Red Shirts overthrew the Spanish Kings and liberated the Kingdom of two Sicilies. In 1861, Victor Emmanuel II was proclaimed as the King of united Italy. Garibaldi and the Red Shirts also freed Central Italy from the control of the Pope.