The correct option is D It lead to economic cooperation among German states and generated a sense of unity among the people.
The Zolloverein was a German customs union that was founded in 1834 during the Prussian rule. It formulated many rules for free trade and economic cooperation among the German states. It abolished the tariff barriers and reduced the number of currencies from over thirty to only two. Eventually, it helped to awaken and raise national sentiment and thus, strengthened the movement for the unification of the fragmented German states.