Which best explains why Germany sided with Austria-Hungary following the assassination of Archduke Ferdinand?
The countries shared a border.
The countries had an existing alliance.
The countries were blamed for his death.
The countries both wanted to build colonial empires.

The countries had an existing alliance.

Explanation:

Germany gave blank cheque assurance to whatever step Austria-Hungary takes against Serbia even if Russia intervenes, Germany was ready to offer its help. Historians have referred to as the carte blanche or “blank check” assurance which marked a decisive moment in the chain of events leading  to the outbreak of the First World War in Europe.

Arch Duke Ferdinand was the Emperor of Austrian Hungary who was assassinated by a Serbian Nationalist on his visit to Bosnia. This demise shook the emotions of Wilhelm Kaiser of Germany who had just visited Archduke Ferdinand just two weeks back and there were a cordial ties between Germany and Austria-Hungary.

Germany sided with Austria-Hungary following the assassination of Archduke Ferdinand-The countries had an existing alliance

Explanation:

the protestant reformation's started in 1517, disturbing the religious and political order in europe´s catholic countries. the outcome was the european wars of religion prosecuted in europe in the 16th, 17th and part of the 18th century. nonetheless, uprisings, territorial disputes, and great power conflicts were also causes of the wars.  

disequilibrium means that either supply is greater than the demand for an available good, or that the demand for a product outstrips the available supply. it implies that the price for a is either too low creating large demand, or too high creating a large surplus of supply.