Why did italy refuse to support its ally germany? it viewed the schlieffen plan as a poor strategy. it did not want to fight the united states. it opposed the treaty of brest-litovsk. it accused germany of starting the war?

Best answer of those choices:

It's a little more complicated than just that -- let me explain.  The Triple Alliance between Germany, Austria-Hungary, and Italy, was intended to be a defensive alliance.  In Italy's view, both Germany and Austria-Hungary were acting as aggressors in starting the Great War (World War I).  So it wasn't a "defensive" position they were in.

Additionally, Italy was seeing greater opportunity in siding with the Allies over against the Central Powers.  Historically, Italy and Austria-Hungary had not been on the same side.  Italy stood to gain some territorial concessions if it sided with the Allies against Austria-Hungary and won.

When the war began in 1914, Italy stayed neutral.  By 1915, Italy declared war on Austria-Hungary and joined the Allies.

a.   it resulted in widespread unemployment.