When the Germans conquered this country, they set up up ports from where they could launch their u-boats. was the name of that nation?

After the Invasion of france, they would launch them off the west coast of france. This would help them get to most of the western and southern countrys borders to stop convoys

c or d both can be the answer

offline recommendation systems option b

because recommendation systems produce a list of two ways

1. through collaborative filtering

or

2. through content-based filtering