When Charles the Simple Ceded French Land to the Viking

When Charles the Simple ceded French land to the Viking chief Rollo,what became of his followers who settled there?

A) They acculturated to French culture,adopting Christianity and becoming famous warriors.
B) They used their new home as a base for taking over the rest of France.
C) They were soon driven out by hostile Frankish knights.
D) They continued their barbaric ways,leaving the duchy weak and divided.
E) They remained a hostile threat to their neighbors until defeated by Otto II.