The main reason the german government signed the treaty of versailles was that they thought the treaty was the only way to secure world peace. they could not afford to pay the high fines imposed by not signing. they believed that signing would keep them from paying restitution. they feared the threat of an attack by the allied forces.

I believe the answer is:  they feared the threat of an attack by the Allied forces

At that time, the german's forces were surrounded by the allies.  The allied forces manage to conduct an airbomb raid to the center of germany's operation and ask them to surrender.

Knowing that German couldn't do anything to handle the allies' forces, they agree to signed the treaty of versailles, in which German boundaries was re-assigned and they are forced to payback all the expenses from the war.

i believe it would be capitalism

increases in demand are shown by a shift to the right in the demand curve. this could be caused by a number of factors, including a rise in income, a rise in the price of a substitute or a fall in the price of a complement.

which the answer is:

b