Monarch butterfly caterpillars are completely dependent upon milkweed as a food source between the larval stage and when they pupate (in a chrysalis) and emerge as butterflies. This relationship can be referred to as: A. facultative parasitism. B. obligate herbivory. C. obligate mutualism. D. niche differentiation. E. facultative mutualism.

C

Explanation:

Mutualism is a relationship between two organisms where both organisms benefit from the relationship. Obligate mutualism is a mutual relationship between two organisms where one or both organisms are completely dependent on the other.

The relationship between monarch butterfly caterpillars and milkweed is that of obligate mutualism because the butterflies rely completely on the nectar they get from the milkweed and the milkweed provides a space for the next generation of caterpillars to survive and the milkweed needs the monarch butterfly to pollinate the plant and increase dispersal.