(A) ** Belgium
(B) Russia
(C) Italy
(D) France
EXPLANATIONS BELOW
Concept note-1: -The German invasion of Belgium on 4 August 1914, in violation of Article VII of the Treaty of London was the casus belli, the reason given by the British government, for declaring war on Germany.
Concept note-2: -Of course, Belgians refused to let them through, so the Germans decided to enter by force and invaded Belgium on Aug. 4, 1914. By doing so, they violated the Treaty of London, which is why Great Britain, that was bound to guard the neutrality of Belgium, entered the war.
Concept note-3: -The German juggernaut smashed its way into Belgium on August 5, initially targeting Belgium’s line of defensive fortresses. The Belgian army was forced to retreat and by August 20 the Germans entered Brussels on its way to France. The Belgians elected not to defend the city and the Germans marched through unhindered.
Concept note-4: -Britain and its Empire go to war Germany’s invasion of Belgium tipped the balance for Britain. At 2pm on 4 August, it issued an ultimatum demanding Germany withdraw its troops. At 11pm, the deadline passed without a reply. Britain declared war.
Concept note-5: -The official explanation focused on protecting Belgium as a neutral country; the main reason, however, was to prevent a French defeat that would have left Germany in control of Western Europe. The Liberal Party was in power with prime minister H. H. Asquith and foreign minister Edward Grey leading the way.