Final answer:
A positive interaction refers to a type of relationship between two species where both species benefit. One example is mutualism, such as the relationship between fungi and plant roots. This type of positive interaction helped with the colonization of land by plants.
Step-by-step explanation:
A positive interaction refers to a type of relationship between two species where both species benefit. One example of a positive interaction is mutualism, in which both organisms benefit from their interaction. For example, the relationship between fungi and plant roots, known as mycorrhiza, is a mutualistic relationship. The fungi provide nutrients to the plants, while the plants provide energy-rich carbohydrates to the fungi. This type of positive interaction helped with the colonization of land by plants because fungi helped plants acquire essential nutrients from the soil, allowing them to grow and establish themselves in new terrestrial environments.