Question

Which of the following best explains why the area between Spain and Gaul was not part of the Roman Empire until 107 CE, even though the surrounding areas were both part of the empire for many years?
This area was populated by highly organized warriors.
Rivers in this region made it difficult to access.
This area was seen as undesirable by the Romans.
Mountains made this region difficult to access.

Answer 1

The best explanation why the area between Spain and Gaul was not part of the Roman empire until that later period was a culmination from both undesireability and difficulty in accessing this region due to its mountaineous nature. So I would wager the answer being both C and D - undesireability and difficulty in access.