Read the following article and answer the question. Article: From Britain to the Middle East and China, engineers and architects are pushing the boundaries of possibility as they strive to create the biggest and the best. Here are recently-selected seven wonders-to-be in the modern world which are near completion. Among these, Beijing Daxing International Airport ranks the first and Hong Kong-Zhuhai-Macau Bridge ranks the third. No.1 Beijing Daxing International Airport, China Beijing Daxing International Airport, which is set to be the biggest airport in the world, is designed by Iraqi-British architect Zaha Hadid. The new Terminal One will have a radial-like plan, designed to reduce passenger travel distances. The construction of the new airport started in 2015 and it is planned to be put into use in 2019. No.2 Kingdom Tower, Jeddah, Saudi Arabia Adrian Smith, the architect who has designed the highest structure in the world, the 829.8 m-high Burj Khalifa in Dubai, is now working on his new project which will smash his own record by this over-a-kilometer-high Kingdom Tower in Jeddah, Saudi Arabia. No one can be sure about the exact date of its completion but most probably the project will be ended in 2019. No.3 Hong Kong-Zhuhai-Macau Bridge, China At about 50 km long, Hong Kong-Zhuhai-Macau Bridge will take the title of the longest water span in the world from another China's bridge in Jiaozhou Bay. The construction started in 2009 and will complete the first session in 2017. No.4 Chernobyl reactor, Ukraine The engineers of the USSR who fought to bring the Chernobyl disaster under control built a concrete sarcophagus to cover the hole that had opened up above the destroyed reactor. A new steel arched structure is being built, to be rolled on rails over the reactor, from which point demolition work can begin using cranes suspended from the new roof. Most possibly it will be finished in 2020. No.5 Hotel Abraj Kudai, Mecca Every hajj, Mecca receives more than two million pilgrims from all over the world. New buildings are being built to accommodate these pilgrims. The... Question: Which building is the highest existing building? Answer:

Options: (I). Burj Khalifa in Dubai. (II). Kingdom Tower in Jeddah. (III). Hotel Abraj Kudai in Mecca. (IV). Chernobyl reactor in Ukraine.
Answer:
(I).