In early twentieth century United States history, which international event helped trigger the first Red Scare by increasing fears of radical revolution?

Introduction / Context:
The term Red Scare refers to periods of intense fear of communism and radical left wing ideas in the United States. The first Red Scare occurred shortly after the First World War. Many Americans worried that a similar revolution could occur in their country. Consequently, it is important to know which international event made these fears seem more real and contributed directly to the first wave of anti communist panic.

Given Data / Assumptions:

• The question asks about the international event that led to the first Red Scare.
• The time frame is the years following World War I.
• Options mention an epidemic in Germany, a revolution in Russia, a murder in Italy and an election in Britain.
• We assume basic knowledge that Red is a colour often associated with communism and that Russia underwent a major revolution in 1917.

Concept / Approach:
In 1917, the Bolshevik Revolution in Russia overthrew the old regime and established a communist government. This event shocked many observers worldwide, including leaders and citizens in the United States. After the war, labour unrest, strikes and bomb scares in America were interpreted through the lens of fear that a similar communist revolution could happen there. The term Red Scare reflects worry about red flags and revolutionary symbols associated with communism. Therefore, the correct answer is the Bolshevik Revolution in Russia, not unrelated events in Germany, Italy or Britain.

Step-by-Step Solution:
Step 1: Recall that the first Red Scare occurred around 1919 to 1920 in the United States.Step 2: Remember that in 1917 the Bolshevik Revolution in Russia created the first large communist state.Step 3: Understand that many Americans feared the spread of similar revolutionary ideas within their own country.Step 4: Examine the answer choices and identify the one that explicitly mentions a revolution in Russia and a communist government.Step 5: Reject references to epidemics, murder cases or elections that had no direct connection to communist takeovers.Step 6: Choose the Russian revolution option as the direct international catalyst for the first Red Scare.

Verification / Alternative check:
History texts on the Red Scare often begin with or quickly mention the Bolshevik Revolution as part of the background. They show how posters, speeches and government documents at the time linked domestic unrest to foreign revolutionary movements. By contrast, specific epidemics in Germany, ordinary criminal cases in Italy or election results in Britain are rarely, if ever, presented as the main cause of anti communist fears in the United States. This confirms that the revolution in Russia is the correct answer.

Why Other Options Are Wrong:
Option A is wrong because although epidemics can cause serious disruption, they do not by themselves create intense fears of communist revolution. Option C is incorrect because a murder case in Italy, unless directly tied to revolutionary movements, would not trigger a nationwide political panic in another country. Option D is also wrong because ordinary elections in Britain, even close ones, did not bring communists to power and were not the primary trigger for the Red Scare in America.

Common Pitfalls:
Students sometimes see the word international and think any foreign event might count, but it is important to connect the type of event to the specific fear. The Red Scare focused on communism and radical politics, not on disease or ordinary crime. A good way to avoid confusion is to link the word Red directly with the communist revolution in Russia and remember that this event made fears of similar uprisings feel more realistic to many people in the United States.

Final Answer:
The international event that led to the first Red Scare was the Bolshevik Revolution in Russia that brought a communist government to power.