The correct answer is A) building a transcontinental railroad.
Renewed sectional conflict in 1854 was triggered by the question of "building a transcontinental railroad."
After teh Kansas-Nebraska Act of 1854, the farmers from the Northern states such as asked the federal government to get access to the territories of the west such as Missouri and Iowa to settle the land and make it work and profitable. That is when the railroad companies supported the idea of the expansion to the west.
The Transcontinental Railroad was an innovative project that would join the East Coast of the United States with the Pacific Coast. The companies Union Pacific Railroad and Central Pacific were selected by the federal government to connect the country after the passage of the Pacific Railroad Act of 1862.