Which sentence is written correctly?
A. The train that is taking us to New York has a full restaurant in the last car.
The train that is taking us to New York has a full restaurant in the last car.
B. The train, that is taking us to New York, has a full restaurant in the last car.

Question

Which sentence is written correctly? 
A. The train that is taking us to New York has a full restaurant in the last car.
The train that is taking us to New York has a full restaurant in the last car.
B. The train, that is taking us to New York, has a full restaurant in the last car.

anonymous · Answer

Answer A is correct. Answer B has several unneeded commas.

anonymous · Answer

The phrase "that is taking us to New York" is restrictive -- it defines which train you mean, and so it cannot be set off from the rest of the sentence with commas.