1. Answer: C. A newspaper article would explain the events surrounding the explosion with quotes from witnesses in a written report; a TV news report would perhaps feature live video of the explosion, audio of witness interviews, and live commentary at the scene of the explosion.
2. Answer: B. Using an illustration, my science teacher explained how the weather cycle works.
3. Answer: B. adjectival clause
4. Answer: A. An explanation of why sitting correctly is so important