Answer: the correct choice is d) 100000 organisms in 0.5 miles.
Explanation: Population density is directly proportional to the number of species(organisms) and inversely proportional to the land area.
population density = number of organisms/land area
Let's plug in the values for all the choices and see which one gives greatest population density.
a) population density =
= 50000
b) population density =
= 13000
c) population density =
= 37500
d) population density =
= 200000
From above calculations, the greatest population density(200000 organism per mile) is for the last choice.
So, the correct choice is d) 100000 organisms in 0.5 miles.