What did the government impose to stop the growing demonstrations?

Correct answer: Curfew

The direct answer is option B, curfew. A curfew is an official order restricting people from going out during specified hours. In the Petrograd unrest, the government used restrictive and forceful measures to control the growing demonstrations; in the school-level account, curfew is identified as the measure in this question. Option A, tax relief, means reducing taxes. It is an economic concession, not a direct restriction on crowds. Option B is correct because a curfew limits movement and can prevent people from gathering. Option C, a new election, is a political process and would not immediately stop a street demonstration. Option D, land reform, changes land ownership or distribution and is unrelated to controlling an immediate protest. Exam cue: when the question asks for a measure used to stop demonstrations, distinguish a coercive restriction such as curfew from long-term economic or political reforms.