Resource partitioning would be most likely to occur between

a. sympatric populations of a predator and its prey.
b. sympatric populations of a flowering plant and its specialized insect pollinator.
c. allopatric populations of the same animal species.
d. sympatric populations of species with similar ecological niches.
e. allopatric populations of species with similar ecological niches.

D. sympatric populations of species with similar ecological niches.

Explanation:

In a sympatric population, two similar species live together in the same niche but do not mate with each other. So when two species share the same niche than competition occurs between them for same resource and space.

So to avoid competition sympatric populations of species divide their niche which is called resource partitioning. This resource partitioning allows two species to co-exist.  

For example, different species of lizard which feed on insects on Caribbean islands partitioned their resource by occupying different physical location to avoid competition. So the correct answer is D.