(A) ** Balkins
(B) Gallipoli
(C) Western Front
(D) Ottoman Empire
EXPLANATIONS BELOW
Concept note-1: -The powder keg of Europe or Balkan powder keg was the Balkans in the early part of the 20th century preceding World War I.
Concept note-2: -The Powder Keg of Europe is a term used to describe the situation in the Balkan Peninsula before World War I. This situation involved the wish of many Slavic people living in the Austro-Hungarian Empire to be free of Austrian rule. This desire was supported by Russia, the largest Slavic nation in Europe.
Concept note-3: -The decline of the Ottoman Empire created a vacuum waiting to be filled by new forces. The Balkans became an unstable theatre in which the interests of the major powers clashed with the national programmes of the emergent peoples of south-eastern Europe.
Concept note-4: -The Balkan Power Keg is a metaphor used by historians to refer to the nationalistic tensions present in the Balkans region of Europe before the 1914 outbreak of World War I.