Answer:
D) the great fortunes made by individuals in oil, steel, and railroads.
Step-by-step explanation:
The Gilded Age of the late 1800s is especially known for "the great fortunes made by individuals in oil, steel, and railroads." This is because, this is a period with the considerable growth in wealth which was as a result of the industrial age and the flamboyant lifestyles, it enabled the wealthy people to enjoy.
Hence, the right answer is option D: the great fortunes made by individuals in oil, steel, and railroads.