Four phrases/ sentences have been removed from the text below. For each question, mark the letter A, B, C, or D on your answer sheet to indicate the correct option that best fits each of the numbered blanks from 9 to 12.

Many young people move to big cities to study or work. Cities offer more jobs and better services. However, living in cities also brings many problems. Compared to the countryside, (9) ________. The cost of living is one of the biggest problems. People have to pay more for housing, food, and transport. Many families spend most of their money on rent. (10) ________. Busy streets and crowded public places make the city noisy and polluted, which can affect people's health. Another problem is the lack of green space. Many people live in small apartments without gardens. (11) ________, so children have fewer chances to play outside or enjoy nature. (12) ________. They are building parks and improving public transport, but it will take time to make cities more comfortable places to live.