Answer:
C.differences in food preferences between two populations of birds.
Explanation:
Reproductive isolation is a type of isolating mechanism which may further lead to speciation.
In this type of isolating mechanisms, the two types of organisms are isolated as they are unable to either mate or even if they mate, they fail to produce a viable progeny.
Reproductive isolation can occur due to :
1. Different mating strategies, time or place.
2. Inability to fertilize.
3.Production of a sterile or viable progeny.
Therefore, from the given option differences in food preferences is not a type of reproductive isolation as it does not follow any of the three listed mechanisms.
