What common effect did the napoleonic wars have on the european countries of spain, austria, and russia?

their economies were by the continental system.

at some point, they all allied with britain against napoleon.

they all had rebellions for independence from france.

they used a scorched-earth policy to defeat napoleon

The correct answer is: Their economies were helped by the Continental System.

After the defeat of Napoleon Bonaparte, the Vienna Congress was held, which was an international meeting held in the Austrian capital, with the aim of restoring the borders of Europe and also ensuring a balance of power to prevent another series of armed conflicts, such as they were the previous French revolutionary wars and, later, the Napoleonic wars.

There in the Congress of Vienna it was determined that Austria regains its possessions in the Balkans, as well as the Tyrol. In the same way, he acquired Lombardy, the Veneto, and Dalmatia, and imposed princes of the House of Habsburg in the Grand Duchy of Tuscany, in the duchies of Parma and Modena, and thereby became the political arbitrator of Italy.

Russia annexes most of Poland that under the name of Congress Poland forms a kingdom whose sovereign is the Russian Tsar, also the Duchy of Finland and the Bessarabia region is annexed.

Spain is not rewarded with territorial gains, but its old dynasties are restored. In this way their economies were helped or improved by the continental system, all as a common effect resulting from the Napoleonic wars.

the answers is b.   environments.