premise: How to take care of your new leopard gecko<br>Get the right environment. A leopard gecko does great in 10-20 gallon (37.9-75.7 l) tanks pretty much all of their life. Options are an aquarium, terrarium, or vivarium.
hypothesis: The article is about how to take care of your new leopard.
reason: Actually, it's about "How to take care of your new leopard gecko" -- a big difference with the omission of just one word, which the model overlooked.