Singapore is building an airport where indoor trees, waterfalls and a 'rain vortex' sit alongside check-in queues, waiting rooms and baggage carousels . Where once sat a car park, there will soon be thousands of trees and plants across 22,000 sq metres of landscaped indoor parklands. This will be joined by a 40m-high indoor waterfall, expected to be the world's tallest. These are the plans for the new 3.5 hectare 'Jewel' development at Singapore's Changi Airport, scheduled to open in 2018; a five-storey, 134,000 square metre complex, mixing natural outdoor plants with modern airport facilities. "The aim behind the introduction of such lush  landscaping is purely to provide all visitors with a memorable experience, one where they are surrounded by nature and greenery,"says Philip Yim, Chief Executive Officer of Jewel Changi Airport Development. Promised sustainability  measures include "extensive usage of photovoltaic panels "to produce renewable energy, as well as encouraging the use of natural lighting and a "high efficiency" air-conditioning system. The indoor waterfall, named the "Rain Vortex", will make use of special lighting effects to change at night into what is promised to be a dramatic light and sound show. "The Rain Vortex is one example of how sustainable design plays an important role in the planning of the attraction," says Yim. 'In the event of a rain storm, the power of the rain water will flow naturally through the oculus. The excess rain water collected will be used for irrigation of the landscaping at Jewel.' Yim quotes the popular reputation Singapore enjoys as "the garden city", where greenery is recognised as an essential part of the urban landscape, an attractive image which clearly inspires Jewel's design. However, it remains to be seen whether, beyond the aesthetic   appeal, Jewel can add genuine environmental things to something as un-environmental as an international airport. To keep the airport developing sustainably, it is advised to  _  .
use no electric lights use more air-conditioners make full use of natural water try to produce renewable energy
Question: Singapore is building an airport where indoor trees, waterfalls and a 'rain vortex' sit alongside check-in queues, waiting rooms and baggage carousels . Where once sat a car park, there will soon be thousands of trees and plants across 22,000 sq metres of landscaped indoor parklands. This will be joined by a 40m-high indoor waterfall, expected to be the world's tallest. These are the plans for the new 3.5 hectare 'Jewel' development at Singapore's Changi Airport, scheduled to open in 2018; a five-storey, 134,000 square metre complex, mixing natural outdoor plants with modern airport facilities. "The aim behind the introduction of such lush  landscaping is purely to provide all visitors with a memorable experience, one where they are surrounded by nature and greenery,"says Philip Yim, Chief Executive Officer of Jewel Changi Airport Development. Promised sustainability  measures include "extensive usage of photovoltaic panels "to produce renewable energy, as well as encouraging the use of natural lighting and a "high efficiency" air-conditioning system. The indoor waterfall, named the "Rain Vortex", will make use of special lighting effects to change at night into what is promised to be a dramatic light and sound show. "The Rain Vortex is one example of how sustainable design plays an important role in the planning of the attraction," says Yim. 'In the event of a rain storm, the power of the rain water will flow naturally through the oculus. The excess rain water collected will be used for irrigation of the landscaping at Jewel.' Yim quotes the popular reputation Singapore enjoys as "the garden city", where greenery is recognised as an essential part of the urban landscape, an attractive image which clearly inspires Jewel's design. However, it remains to be seen whether, beyond the aesthetic   appeal, Jewel can add genuine environmental things to something as un-environmental as an international airport. To keep the airport developing sustainably, it is advised to  _  .
A. use no electric lights
B. use more air-conditioners
C. make full use of natural water
D. try to produce renewable energy
Answer: