The bed nets protect people from mosquitoes longer than of the previous made ones as this is upgraded and highly tested in order to determine its capacity and the uses of it in a way it last longer and protects people from insects that causes disease such as mosquitoes.
The studies are designed this way b/c it removes the power of suggestion and the double-blind study keeps both researchers and participants in the dark. So this compared to who is receiving the treatment which is relevant b/c it stops the researchers from accidentally overbalancing the study participants, or unintentionally favoring their assessment of the conclusions.
Answer:
A. They must compete for essential resources.
Explanation:
I believe it is geographic isolation. Hope it helps.
