Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the option that best fits each of the numbered blanks from 18 to 22.

The Tokyo Subway system is one of the most efficient and expansive public transportation networks in the world. The system, with its over 13 lines and hundreds of stations, ___(1)___. Designed to be fast and punctual, the trains run frequently and on time, making it an essential part of daily life for Tokyo residents. With its cutting-edge technology, the subway system is capable of managing high passenger volumes during peak hours.
The Tokyo Metro covers the central districts and is fully integrated with other forms of public transport. It connects key locations such as shopping districts, business centers, and residential areas. These trains ___(2)___ are equipped with modern amenities such as air conditioning, Wi-Fi, and automatic ticket machines. This makes traveling around the city not only efficient but also comfortable for passengers.
The Japanese government continually invests in expanding and modernizing the subway network to meet the growing demands of the population. ___(3)___, the system now boasts advanced technologies such as automated train operation and energy-saving measures. ___(4)___.
In addition to its efficiency, the Tokyo Subway is also committed to environmental sustainability. The system has implemented green initiatives such as energy-saving trains and the use of solar power in some stations. ___(5)___.