Because he proved that the earth wasn't at at centre of the solar system like everyone thought it did. It also showed the sun doesn't move, it's the earth moving around it.
The correct answers are as followed:
1) Brainwashing and re-education- The Khmer Rogue, the group responsible for the genocide in Cambodia, convinced citizens that "new people" were the problem in Cambodia. The term "new people" refers to anyone who was influenced by western ideas.
2) Seizure of private property- Thousands of Cambodian citizens, especially in the city centers, had their property confiscated by the Khmer Rogue.
3) Destruction of Buddhist temples.
Be more responsible than the house
