What was the 1932 event that ended absolute monarchy and established a constitutional system?

• A Siamese Revolution of 1932 ✓
• B Palace Revolt of 1912
• C Manhattan Rebellion
• D Boworadet Rebellion

The Siamese Revolution of 1932, led by the Khana Ratsadon (People's Party), bloodlessly ended nearly 700 years of absolute monarchy, introducing Siam's first constitution.