The answer is B. This is false.
Britain entered WWI under a moral and legal obligation to protect Belgium, under the treaty of London signed in 1839. After the German invasion of Belgium in 1914, Britain decided to come to the aid of Belgium and France and subsequently declared war on Germany.
Britain suffered horrendous casualties, lost much of its vast wealth, and surrendered her paramount position as the leading power of the world. But without Britain's effort, Germany would have dominated western Europe. Therefore, for moral, legal and strategic reasons, Britain's participation in the first world war was justified.
