The central idea is what the main thing. For this, I think the central idea is simply Cactuses.
I'm not sure what another supporting detail can be, but if there's a back side, or another page about cactuses, I can sure help! But if that's the only side, ask your parents. xD
Answer:
start with a description of the surroundings
Explanation:
While starting a story, you should give the audience a perfect image of where they are standing at the beginning. When they have the image of their character's position, they could easily get along the path.
Force majeure I believe so.
