Which of these took place in promontory, utah, in 1869?
a) the largest discovery of silver in american history
b) the completion of the transcontinental railroad
c) a massacre of cheyenne indians
d) a massacre of sioux indians

B) the completion of the Transcontiental Railroad

Explanation:

Promontory Point, Utah, is associated with the completion of the Transcontinental Railroad. It took seven years to complete and was of vital importance both in boosting the country's economy and in linking the United States together following the Civil War.