The Allied faction, most notably the British, has gained the upper hand during the first world war due to their acquisition of various oil fields. The oil has powered their military vehicles most notably its naval fleet and the introduction of Mark V tanks that posed significant advantage at the course of the war.
The answer is D, having to fight a two-front war.
The Schlieffen plan was the German strategy to quickly take out France so that they could focus all their troops on Russia.
The Missouri Compromise (1820) - Missouri's Southern border to be taken as the line of latitude extending West as the frontier of slavery.
Japan<span>: Japan's Yamato dynasty traces its origins back to 660, making it the oldest continuous hereditary monarchy in the world. The 79-year-old Emperor Akihito has reigned since 1989 and is, according to legend, the 125th emperor in his line, though there's some debate as to the exact count of emperors</span>
