Which turning point changed the February movement from a street demonstration into a crisis of rule?

Correct answer: Soldiers' mutiny and joining the people

The central concept is the collapse of coercive authority. A street demonstration may remain a protest against a government, but it becomes a crisis of rule when the government loses the forces required to enforce its orders. In Petrograd, soldiers’ mutiny and their decision to join or support the people meant that the Tsarist regime could no longer depend confidently on the army to restore order. This transformed public protest into a direct challenge to political power and made the continuation of autocratic rule uncertain. Option A is correct. A private feast, a good harvest and a foreign trade tax did not cause this immediate breakdown of state authority.