Who was the titan of industry, or the so-called robber baron, most closely associated with the railroad industry? (points : 1)
carnegie
gould
rockefeller
morgan

It would be "Jay Gould" who was the titan of industry, or the so-called robber baron, most closely associated with the railroad industry, since his dealing in the railroad industry made him the 9th richest man in the United States while he was alive. 

The robber baron you've mentioned would be Jay Gould (1836 - 1892). He is a historic figure that has been hated by many. He has also been vilified due to his role in the railroad industry and his role as a prospector at the end of the 19th century US. Furthermore, he was recently retrospectively voted as one of the worst CEOs of all time.