One example of a recent technological advancement that is helping people to overcome a physical boundary is __________.

A.
a tunnel for a high speed train underneath the Alps
B.
a bridge for a high speed train crossing over the Nile River
C.
a luxury cruise ship that travels from Mexico to Japan
D.
a steam-powered train that travels across the Rocky Mountains

Please select the best answer from the choices provided
A
B
C
D