Here are the correct answers circled:

1. The Japanese stay healthier **B. because** they eat a lot of fish.
2. There are a lot of **A. homeless** people after the earthquake two days ago.
3. We stayed to clean up the campsite **D. since** it was full of rubbish.
4. We **B. donated** old clothes and canned food to the people in the flooded area last week.
5. A volunteer always helps other people willingly and **B. without** any payment.