What year did the first roller coaster, the "Switchback Railway," open?

The "Switchback Railway" opened in 1884, marking a significant milestone in the history of roller coasters. This ride operated at Coney Island in New York and is recognized as one of the first roller coasters designed for amusement park use. Its initial layout used a simple design featuring a series of hills which created a thrilling experience for riders, setting the foundation for modern roller coasters.

The year 1884 is noteworthy not only because it represents the advent of roller coasters as we know them today but also because it was a time when amusement parks were becoming popular attractions. The success of the "Switchback Railway" paved the way for many other roller coasters that followed, leading to the diverse and innovative designs we see in parks around the world today.

Other years listed as options reflect times after the opening of the "Switchback Railway," which makes them less relevant in the context of the question. Thus, 1884 stands out as the correct answer and is a key date in roller coaster history.