Generally speaking, it was difficult for American ground forces to clear areas of guerrillas because "The guerrillas hid themselves from American forces" and "<span>The guerrillas fled while the ground forces were in their area". </span>
I believe the answer is: A. nationalism
The hundred years wars create a bitter memory between the French citizens toward the citizens of the British Empire.
Through this military rivalry, the feeling of loyalty towards own country is dramatically increased for both French and British Citizens.
it has because after 9/11 there were stricter security checks and there were laws put in place to help prevent another event like this. I hope this helps...