Which describes a major challenge facing the builders of the transcontinental railroad a. spanning the grand canyon b. crossing the serra nevada c. bridging the rio grande river d. this none, but no under lake erie

The correct answer is B. A major challenge facing the builders of the Transcontinental Railroad was crossing the Serra Nevada.

Explanation:

The Transcontinental Railroad route followed the main roads used for the opening of the West, the so-called Oregon Route, the Mormon Route and the California Route, and the Pony Express. Going from Council Bluffs (Iowa), it followed the Platte River through Nebraska, left the traditional route to cross the Rockies in the Great Divide Basin in Wyoming and then stop through northern Utah and Nevada in the Great Basin before crossing Sierra Nevada to Sacramento.

Six months after the Pacific Railroad Act, on January 8, 1863 Governor Leland Stanford ceremoniously laid the "first stone" to begin construction of the Central Pacific Railroad in Sacramento, California. The Central Pacific made great progress throughout the Sacramento Valley. However, they reduced the progress of construction, first by the foothills of Sierra Nevada, then by the mountains themselves and, even more importantly, by winter snowstorms.

i know social security wasn't one.

explanation:

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warfare was the primary means of cultural transmission in both regions.