In the 1850s, the issue of slavery complicated the proposal to build a transcontinental railroad, as select one: a. it raised the question of whether or not slaves would be used as railroad labor. b. non-slaveowning northerners and slaveowning southerners could not agree on a route. c. british banks refused to fund the project as long as slavery existed in the united states. d. it raised the question of whether or not slaves would be used as railroad labor, and british banks refused to fund the projects as long as slavery existed in the u. s. e. none of these answers is correct.