Read the following passage and mark the letter A, B, C, or D to indicate the correct answer to each of the questions.

Biodiversity on our planet is rapidly declining mainly due to human activities such as climate change and pollution. That is why governments and organisations have taken measures to protect wildlife and stop biodiversity loss. The emergence of artificial intelligence has dramatically changed wildlife protection. Conservationists are now turning to AI to find solutions to the rapid loss of plants and animals.

One of the biggest threats to endangered species is poaching for commercial purposes. Therefore, it is essential to stop this illegal activity in forests and nature reserves. However, rangers, whose job is to take care of such large areas, find it hard to monitor wildlife and prevent poaching. That is why many national parks are using AI cameras to track both animals and poachers. Furthermore, the cameras can send real-time updates to rangers' phones and alert them to any illegal activities within minutes. The cutting-edge technology is even effective at night when poachers operate under cover of darkness. The AI cameras are designed to automatically notice any illegal cars or boats entering forests or other protected areas.

Another factor responsible for the decline in biodiversity is habitat loss. When natural habitats or environmental conditions change, it's nearly impossible for scientists to identify the changes until they discover strong evidence. For example, some countries have faced increasing pressure from climate change and economic growth, and have lost a huge amount of surface water. However, the situation has only been discovered with the help of artificial intelligence. Without AI, scientists could not have identified and analysed the changes nationwide. AI has played an important role in collecting data and analysing the factors affecting wildlife, thus helping governments and organisations respond to critical situations in the quickest way possible.

The word they' in paragraph 3 refers to _______.