Answer:
A scientific theory is a well-substantiated explanation of some aspect of the natural world, based on a body of facts that have been repeatedly confirmed through observation and experiment. Such fact-supported theories are not "guesses" but reliable accounts of the real world.
Explanation:
I'm gonna go and say it's parenchyma but I'm not 100% sure
Well there are three reasons
it drains into rivers, streams, etc. or
it seeps into soil and gather underground as ground-water
or
falls into high mountains and freeze and in the summer it will melt and flows into the rivers
The struggle for the civil rights
One explanation could be the differences in climate (environmental factors). The climate in northern Mexico could support the reproduction of the mosquito species, which is a vector of the dengue virus. Other environmental conditions that influence its endemicity could include living conditions and sanitation. The other possiblity could be that the people in the US have developed immunity for the disease, therefore, are unaffected even when infected by the virus.