All of these are describing
a) the erie canal.
b) the panama canal.
c) the pony express.
d) the cumberland road.

The correct answer to this open question is the following.

All of these are describing important means of Communication.

The Erie Canal, the Panama Canal, the Pony Express, and the Cumberland Road are important means of communication.

In the Northeast region of North America, the Erie canal has represented an important mean of communication and transportation of people and goods. The Panama Canal changed the way goods were transported via cargo ship because it helped to cross Central America through Panama, instead of navigation down south the continent. The Pony Express was a mail service using riders and horses to take the mail to distant places in the mid1800s. The Cumberland Road was the major highway built by the federal government in the US.

it refers to race, i am pretty sure this was a popular term in nazi germany or something.

did you check the study guide?