Answer:
The correct option is D) increased passport security at internal borders
Step-by-step explanation:
The creation of the European Union helped to forge a unique international community where there countries do not have any borders and both citizens and goods and travel across without any checks.
This means a citizen from England can easily travel to e.g. Hungary without any need of a passport.
This obviously helped to create a boom in not only tourism but also trade between those countries. immigration has already increase between the countries so if someone from England wants to retire in Spain or someone from Greece wants to find a job in Germany, it is as simple as moving within your own country.