The correct answer is D. To form an alliance with the Roman emperor
Step-by-step explanation
The Germanic tribes were an original community from northern Europe. The tribes were made up of a large part of the pre-Roman peoples and barbarian peoples. During the time of the Roman Empire, they were related to it in a violent way because they were the ones who invaded it during the episode known as the so-called Germanic invasions that caused the fall of the Western Roman Empire. Therefore, it can be affirmed that the Germanic tribes did not invade the Roman Empire to establish an alliance with them, but instead invaded it to cause its overthrow in Western Europe. So the correct answer is D. To form an alliance with the Roman emperor