This is most likely specifically asking for World War I. 
The first thing is rather not a gain, but a trust. Most of Europe, Asia, as well as the Middle East and Africa, were split into two camps. These camps were alliances, known as the Central Alliance (the German & Austrio-Hungary camp), and the Allies (The British & French camp). 
The war was triggered by the assassination of Archduke Franz Ferdinand and his wife Sophie by a Serbian Nationalist who wanted to see a free Serbia. While Serbia was open to paying for reparation, Austrio-Hungary threw away the table in hopes of conquering and claiming Serbia for their own. The failure for the gears of war to stop before then was what caused the countries to go at war. Each country was bound by their alliance contract to help their members at need, and so it set off a chain reaction that ensued into a global war. 
They had nothing to gain, but to keep their own honor, the survivability of their state, and the trust of their allies. 
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Discrimination, wars, poverty
        
             
        
        
        
Two conflicts-the War of the Spanish Succession and the war in the Baltic-almost merged into a single pan-European war. Even though Russia and Prussia appeared on the international scene, the balance of power that emerged after the Thirty Years ' War was never broken. None of the great powers could achieve unconditional dominance over rivals.  
In the 18th century, France was weakened. Sweden, Spain, and Holland withdrew to the second roles. The strongest players looked England and the Austrian Empire. Prussia and Russia were gaining political weight.
 
        
             
        
        
        
Answer:  B) The Organic Theory
Details:
The Organic Theory of geography -- or maybe more accurately, of geopolitics -- was proposed by German geographer Friedrich Ratzel in 1897.  He suggested that nations function similarly to living organisms.  The controversial part of his theory was that the way a living organism takes in nourishment to grow and thrive, strong nations naturally will nourish and expand themselves, taking in weaker nations or cultures around them.  Ratzel coined the term "Lebensraum" (German for "living space"), which originally, in his view, meant the space for a strong nationalist culture to grow.  His writings came only a few decades after the German Empire had been reborn as the "Second Reich" (second kingdom), a renewal of the older "Holy Roman Empire" of German states as they were linked together in the medieval era.  Ratzel's ideas about "Lebensraum" later were picked up by Hitler and the Nazis as a justification for expanding German territory and taking over neighboring countries.  Germany's expansion under the Nazis as the "Third Reich" led to World War II in Europe.