Library with a glass floor

As a series of glass-floored attractions have opened to the public in China, a college in Zhengzhou, Henan province followed the trend - using glass as the floor of its newly-built library. The fifth floor of the library, paved by more than 100 glass tiles, provides a thrilling view for students who are brave enough to walk on it. Some young girls even danced ballet on the panels.

On which floor was the library paved by the glass tiles?

A. 4th floor

B. 5th floor

C. 6th floor