Question

the leaders of austria-hungary blamed the serbian military for the death of archduke fra ferdinand. what did they do one month after the archduke was shot? they declared war on serbia. they appointed franz joseph as the new archduke. they created a new alliance with serbia. they murdered the king of serbia.

Explanation:

Archduke Franz Ferdinand was assassinated on June 28, 1914. Austria-Hungary blamed Serbia and issued an ultimatum on July 23, 1914. When Serbia's response was deemed insufficient, Austria-Hungary declared war on Serbia on July 28, 1914—one month after the assassination. The other options are incorrect: Franz Joseph was already Emperor of Austria-Hungary (not a new archduke), no alliance was formed, and the King of Serbia was not murdered by Austria-Hungary at this time.

Answer:

They declared war on Serbia.