环境问题描述 — 英语选择题

Tom 正在写关于城市环境问题的短文。下面哪一句能正确描述环境问题并给出合理建议？A. Our city is clean and beautiful, so we should throw rubbish everywhere. B. Smoke from cars makes the air dirty. We can take the bus to school. C. The river is dirty because fish swim in it. D. Rubbish makes the streets clean, so we like it.