What challenge did the United States pose to Mexico after the Mexican Revolution? A) It imposed strict tariffs on a variety of Mexican products. B) It launched military campaigns into Mexico to protect US borders. C) It blocked its border with Mexico to keep immigrants out. D) It sent troops to Mexico in an effort to seize its vast oil fields.

What the question is really asking

You are looking for the main way the United States directly challenged Mexico in the period right after the revolutionary upheaval, especially in terms of foreign intervention.

Why option B fits the history

The most concrete challenge was US military intervention tied to border violence and instability. The key example is the 1916 Punitive Expedition (Pershing Expedition), when US forces entered Mexico after Pancho Villa's raid on Columbus, New Mexico, aiming to protect US territory and pursue Villa.

Why the other choices are not the best match

• A (strict tariffs): US-Mexico tensions were more about recognition, security, and investments than a standout post-revolution tariff campaign as the defining challenge.
• C (blocked the border): There were restrictions and policing, but a full border blockade to keep immigrants out is not the standard description of the major post-revolution challenge.
• D (troops to seize oil fields): Oil was a major diplomatic conflict (especially around Article 27 and foreign ownership), but the US did not simply send troops to seize Mexico’s oil fields as the defining post-revolution action.

Quick takeaway

When a question highlights a US “challenge” to Mexico after the revolution, the safest match is border-related military intervention, which is option B.