Concept:
- Mazzini worked from exile, so the city in the answer has to be one outside Italy that offered political shelter.
- Pairing each option with the event it is actually famous for exposes the answer by elimination.
Step 1: Tag Vienna with its real association.
Vienna belongs to the peace settlement of 1815 and to Duke Metternich, who led the conservative order. It is not a place where a revolutionary society could be founded in secret. Option (D) is out.
Step 2: Tag Marseilles with its real association.
Marseilles is the city where Mazzini founded Young Italy, an organisation aimed only at the Italian states. The question asks about Young Europe, which was the wider body. Option (C) is out.
Step 3: Weigh Brussels against Berne.
Brussels does not appear in the account of Mazzini at all. Berne, in Switzerland, does, and Switzerland was the usual refuge for political exiles of that period.
Step 4: Fix the answer with the aim of the society.
Young Europe drew members from Poland, France, Italy and the German states, so it needed a neutral base that exiles from several countries could reach. Berne served exactly that purpose.
Final Answer: (A) Berne