AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
Option B — Sardinia-Piedmont was the only Italian state ruled by an Italian princely house and took the lead in unifying Italy through war and diplomacy.
The passage states that Chief Minister Cavour led the movement to unify Italy, engineered a diplomatic alliance with France, and defeated Austria in 1859 — all through Sardinia-Piedmont. Ultimately Victor Emmanuel II (its king) was proclaimed king of united Italy in 1861. Option B is directly supported by the source. Other options contradict the text (e.g., Austria opposed unification; Bourbon/Spanish rulers were driven out, not willing collaborators).