Why is 2010 considered a significant year?

Read the following passage carefully and choose the most appropriate answer to the question out of the four alternatives.

The Eiffel Tower is an iron lattice tower located on the Champ de Mars in Paris. It was named after the engineer Gustave Eiffel, whose company designed and built the tower. Erected in 1889, it was initially criticised by some of France's leading artists and intellectuals for its design, but has become both a global cultural icon of France and one of the most recognisable structures in the world. The tower is the tallest structure in Paris and the most visited monument in the world; 6.98 million people ascended it in 2011. The tower received its 250 millionth visitor in 2010.

The tower is 324 metres, about the same height as an 81-storey building. During its construction, the Eiffel Tower surpassed the Washington Monument to assume the title of the tallest man-made structure in the world. The tower has three levels for visitors, with restaurants on the first and second. Tickets can be purchased to ascend by stairs or lift to the first and second levels. Although there are stairs to the third and highest level, these are usually closed to the public and it is generally only accessible by lift. As a global landmark, the Eiffel Tower is featured in media including films,
video games, and television shows.