Diabetic retinopathy as a result of chronically high blood sugar can cause blood vessels in the retina to hemorrhage, distorting vision.
Answer is A. A population becomes separated by environmental factors into two groups that do not reproduce with one another.
When a population of a species become geographically separated then gene flow between them stops. Over a period of time, the population may become genetically different in response to the natural selection due to different environments. Selection and genetic drift will act differently on these two separated populations. This will results into two separate species. This type of speciation is called allopatric speciation.
Answer:
frequency of the blue (B) allele 
frequency of the red (R) allele 
The number of blue plants expected is 
The number of red plants expected is 
The anticipated number of violet plants is 
Calculated chi square value
Explanation:
Frequency of blue allele is
Frequency of blue allele is equal to sum of frequency of BB and half of frequency of BR

Frequency of other allele

Chi Square test
See the attached file
The number of blue plants expected is 
The number of red plants expected is 
The anticipated number of violet plants is 
Calculated chi square value