Before the nation's first transcontinental railroad was completed, travelers to the Pacific Coast used which forms of transportation? a. ship, wagon b. dugout canoe, dirigible c. horse d. All of the above are correct.

a. ship, wagon

Explanation:

The shortest driving distance between the east and west coast of the USA is 2,671 miles and is along Route 80. In those days they did not have roads for cars so the journey must have been longer which makes it highly improbable that a house could have completed that journey and seeing as there is no canal splitting the USA in 2, a canoe could not be used.

A ship going across the world and a wagon going across the Continental USA seem the most likely of options.

i would say b. research typically uses a variety of sources