Answer:
B. first transcontinental railroad
Step-by-step explanation:
Panama Canal railroad started operating in 1855. and it was the first railroad that connected two oceans directly. Building the canal back then was a difficult task, so they have decided to build the railway first.
The railway was significant in the later construction of the Canal – it provided the perfect means of transportation for material, workers, and equipment necessary for the construction. It ran from the Atlantic Ocean to the Pacific Ocean, over the Isthmus of Panama, and was the first transcontinental railroad in the world. The railroad still is in function today.
Panama Canal was started in the 1880s, following the parallel route of the railroad. It started operating in 1904.