Germany's response to Austria-Hungary's request for aid was: A refusal to provide any assistance A request for more information A promise of unconditional support A suggestion to negotiate with Serbia

## Step 1<br />This problem is a historical question related to the events leading up to World War I. The question is asking about Germany's response to Austria-Hungary's request for aid. <br /><br />## Step 2<br />The options provided are: A refusal to provide any assistance, A request for more information, A promise of unconditional support, and A suggestion to negotiate with Serbia. <br /><br />## Step 3<br />The correct answer is "A promise of unconditional support". This is because, in the context of the events leading up to World War I, Germany had promised unconditional support to Austria-Hungary. This promise was part of the complex web of alliances and treaties that characterized the pre-war period in Europe.