(A) France
(B) ** Russia
(C) USA
(D) UK
EXPLANATIONS BELOW
Concept note-1: -The United Kingdom is the only country of the Big Four which is not a member state of the European Union having ended its membership in 2020, pursuant to a referendum held in 2016.
Concept note-2: -Answer and Explanation: The selected option is Option (a) Carlton & Co.
Concept note-3: -Russia, Austria, Britain and Prussia were the Big Four in the meetings.
Concept note-4: -Switzerland did not attend the Congress of Vienna. The countries which met in Vienna were Russia, Prussia, Britain, and Austria.