The answer is:
A. By 1800, the Holy Roman Empire was little more than a loose collection of separate states.
B. The people of the German states shared customs and language but did not think of themselves as belonging to one nation.
C. The German-speaking people began to feel a common bond with each other when Napoleon conquered them and they fell under French rule.
All the statements are correct because Napoleon's conquests aroused feelings of nationalism in which people began to experience a new sense of unity. As a consequence, the revival of democratic revolutions and nationalism caused the German unification.