What is the observation of a naturally occurring behavior, without intervention in the situation?

How is the introduction of the cane toad to queensland, australia an example of the unintended consequences of using non-native species to control pests? (site 1)

Spray-applied coatings must be applied according to transfer efficiency standards using what technologies? a) high volume, low pressure (hvlp) guns b) electrostatic guns c) airless guns d) all of the above

B. speculate about one positive way and one negative way that this boundary has affected the geographical units it separates over time.