Answer:
A. 7:13
Step-by-step explanation:
The number of observed adults with the genetic marker is 350 out of 1000.
The number of observed adults without the genetic marker is 1000-350 =650 out of 1000.
Therefore
the ratio of observed adults with the genetic marker to observed adults without the genetic marker
equals
[tex]\frac{350}{650}[/tex]
When we divide both sides by 10 and then by 5 we get
[tex]\frac{35}{65}[/tex] = [tex]\frac{7}{13}[/tex]