The germanic tribes were able to invade britain because the crumbled.

The Germanic tribes were able to invade the Britain because of the western half has crumbled by which they were able to push the Romans out, where in, Romans has taken hold of the Germanic people and by pushing them out, they have the power to invade the Britain.

a is correct

hope this let me know if it is right

“the battle of stalingrad is not a turning point necessarily in strategic terms, because a lot more has to be done before the soviets can be certain of defeating germany,” says renowned world war ii historian richard overy. the germans had fought nearly a thousand miles across the soviet union to get to stalingrad.