Which building did the Empire State Building surpass as World's Tallest Building?

And the answer is ...

b) Chrysler Building

Although the Washington Monument, Eiffel Tower and CN Tower all claimed the title of world's tallest freestanding structure at one point, the Chrysler Building held it as the Empire State Building was being built. Both buildings were commissioned to bring the title back to the United States, since the Eiffel Tower beat the Washington Monument in 1889.