It depends on what you take to be the beginning and what the end. It lasted two years if you understand it as from the time it was revealed to the time Nixon resigned. It lasted 5 years if you take it from the time Nixon began doing it to the time he resigned.
A. Building a network of roads.
Terraces
^^^ would be the right answer.
The February Revolution was the first of the two revolutions that took place in 1917 and that ended for good the tsarist Russian Empire.
The revolution emerged near Petrograd (current St.Peterburg) that was the capital of Russia at the time. Russian people was disatisfied with the monarchy and the food rationings. Mass demonstrations were celebrated and there were violent confrontations against the police and gendarmes that remained loyal to the tsar (while the army sided with the revolutionaires). <u>This conflict led to the abdication of Tsar Nicholas II and to the end of the Romanov dynasty. </u>