题目内容：

阅读短文，从文后的五个选项中能填入空白处的最佳选项，选项中有一项为多余选项。

Endangered dolphins are beautiful animals that needed to be saved. It may interest you to know there are about six different types of dolphins that are endangered. Many of them are river dolphins and they are very close to being lost forever if we do not take the time to care for them. The following is the reason why they are in danger.

1. Dolphins can often get stuck(卡) in these nets and they may die. Another problem is the fact that many people and different countries will hunt for dolphins as food.

2. When the oceans and rivers are polluted, it affects the very environment where these beautiful creatures are living. It may be important to also keep in mind that the dolphin is towards the top of the food chain. 3. If these small animals are affected by the pollution as well, there really is no safe place for the dolphin to go.

4. You can also pay attention to the land around you. Do not litter and stop if you do. Spend time on the weekend cleaning up trash in your area and recycle what you can. You play a large role in this whether you believe it or not. So, find out what your role is related to endangered dolphins and work towards a positive change.