Which alternative hypothesis is made far less likely by having three r and k lines, rather than one of each?

Both the populations of Drosophila seem to have the same gene for foraging behavior

Therefore, the alternative hypothesis which is made far less likely by having three R and K lines, rather than one of each is: 

The difference between the R and K lines is the result of environmental differences in the food availability of their habitats.
 

Mutations are changes in the dna

If the experiment was perfomed more then once and you get the same results