What was the Sears Tower in Chicago renamed to?

Here is the question :

WHAT WAS THE SEARS TOWER IN CHICAGO RENAMED TO?

Here is the option for the question :

Willis Tower
Marquette Building
John Hancock Center
Tribune Tower

The Answer:

And, the answer for the the question is :

Willis Tower

Explanation:

[STC002512] If you’ve ever been to the Windy City, there’s a good chance you’ve been inside one of the city’s famous glass observation decks, which allow visitors to stand more than 103 floors above downtown Chicago in an experience that is shockingly unsettling but ultimately satisfying. This took place for a number of years at a tall building in Chicago that was formerly known as the Sears Tower. However, in 2009, the name of the city’s highest structure was changed to the Willis Tower. In spite of the formality, a significant number of people in the area, as well as tourists, still refer to it by its iconic moniker, and they presumably will for a considerable amount of time.