Since it’s the end to the paragraph, i feel like this is the perfect sentence to end the paragraph, it shows that the reader can help not only one species of butterfly but others too, just by plants new plants that support butterflies into their gardens.
It makes the biggest impact on the reader. When writing a article about something as important as this generally what an author will do to captivate the attention of the audience is to make it clear exactly how dire the situation is. It important to make sure that the reader knows that this topic is important. So I would say that ending the first paragraph with something as impactful as #1 would be the best choice, as you really want to draw your reader in and make them acknowledge the topic, it will give the reader a sense of urgency to understand what is going on.
I hope that helped, but incase you didn't understand a word of that;
Basically you want to make sure that the reader of this essay is dead set on learning what is going on with the butterflies, so you want to highlight that there is something BIG going on and #1 really helps to be like "hey there's a problem here!"