Step 1: Understanding the Concept:
This relates to the immediate causes of World War II and Nazi propaganda.
Step 2: Detailed Explanation:
- Assertion (A): Hitler demanded the return of the Free City of Danzig and the Polish Corridor to provide a link between Germany and East Prussia. Poland's refusal led Hitler to attack Poland on September 1, 1939. This is true.
- Reason (R): To justify the invasion to the world and the German public, Hitler accused Poland of committing atrocities against ethnic Germans. He even staged a fake attack on a German radio station (the Gleiwitz incident) as a pretext. This is also true.
- The accusation in (R) was the specific justification used to launch the military action described in (A).
Step 3: Final Answer:
Both statements are true, and (R) provides the direct pretext/explanation for (A).
Hence, the correct option is (C).