People live in different parts of the world and lead different types of lives. Their lifestyles change across the different areas in the world. What is the difference between a city and country life? Let us see. We can see the modern facilities everywhere in the city like the Internet, telephone, television and satellite communication facilities are widely available in the city. A majority of families in the city are enjoying this technological advancement. The increasing population has led to an imbalance in human population. More and more industries have led to environmental problems like pollution. However, the rise in economic growth has resulted in a self-centered nature of society. While technological advancement has brought the world closer, human beings have gone far apart from each other. The country is not crowded with constructions all over. Houses are rather widely spaced with enough room for fields and gardens. The country is the only area fortunate enough to house the  _ . People in the country live in close to nature. Apart from people, there is room for pets and animals that help keep a balance in nature. Due to a lesser number of people in the country, it is not overcrowded by people. These areas have least amounts of pollution. Pollution is less also because of very less number of industries in the country. The life may not be as enjoyable as that in the city, but the people there are generous, kind and friendly. The country is the one where humanity  is still alive. Every coin has two sides to it. While we can't enjoy expensive things and technology in the country, it is rich in its relationship with 'nature'. The city life is modern in technology and career opportunities. However, the falling humanity and a bad environmental balance affect the bright future of city life. According to the passage, the main reason for pollution is   _  .
technology and economy population and industries population and humanity industries and balance.