Listen to the passage and answer the three related questions.To access the questions, click on 1, 2 and 3 respectively. After reading the four choices, click on the response that best answers the question.The following is an example:- Since the 1980s, people have become more aware of the environment. The recycling of cardboard, plastic, glass and paper has grown out of this awareness. - People have also finally realized that much of industry’s progress, based on the use of fossil fuels, is damaging the planet. - Did you know that scientists have long been trying to develop alternative sources of energy, like tidal power? - Yes, tidal power stations could use the power of the tides to supply households with electricity. - There’s also solar power, but its use is dependent on weather conditions!What is the main topic of this conversation?