B is correct answer because among these options it was the only war. It was led in 17th Century and it was the biggest religious war led on the soil of Western Europe. Many countries including Sweden, France, Spain and Habsburg Monarchy were involved.
A is wrong because Edict of Nantes is a document according to which Huguenots in France gained religious liberties.
C and D are wrong because this are two processes connected to the reform in the Catholic church.
