I think you mean the Golden Spike which is the ceremonial final spike driven by Leland Stanford to join the rails of the First Transcontinental Railroad across the US connecting the Central Pacific and Union Pacific railroads in 1869 in Promontory, Utah.
I would say A and B are correct.
What are you specifically looking for in this answer?
The answer is d, progressives were the people who wanted anti-trusts, safer working conditions, and minimum wage.