Option 1: Britain does not have the method of amending the Constitution by popular veto. In Britain, the Constitution is based on parliamentary sovereignty, where the Parliament has the ultimate authority to make and amend laws.

Option 2: Switzerland is the correct answer. Switzerland has a unique system called popular initiative, where the citizens can propose amendments to the Constitution through petitions. If a proposal gathers enough popular support, it is put to a national vote, and if the majority of voters approve it, then it becomes part of the Constitution.

Option 3: Russia does not have the method of amending the Constitution by popular veto. In Russia, the Constitution can be amended by the legislature through a legislative process.

Option 4: India does not have the method of amending the Constitution by popular veto. In India, the Constitution can be amended by the Parliament through a special procedure that requires a two-thirds majority in both houses.

Therefore, the correct answer is option 2, Switzerland.