Which is not a reason why few early south american peoples created large scale civilizations?

a)it is hard to unite people separated by dense forests b)the landscape of the continent is very rugged c)there are very few resources on the continent d) people lived great distances apart from one another

can you explain a little further maybe give multiple choice? ?

the invasive species was introduced due to commercial purpouses, as there was a demand for fur clothes and hence, a business opportunity connected to this product. actually, it was when the nutrias scaped, causing harm to the us ecosystems when they acquired the status of invasive species. in this case they have caused an environmental problem, but it could have affected also economic interests or even human health.