Which of the following is a defining characteristic of mutualism?

Mutualism is a type of symbiotic relationship between two species where both parties benefit from the interaction. This characteristic is crucial for understanding how species interact within ecosystems. The essence of mutualism lies in its positive outcome for both organisms involved, which can lead to improved survival, reproduction, or resource acquisition for each species.

For example, consider the relationship between bees and flowering plants. Bees obtain nectar and pollen from flowers, which they use for food. In return, while visiting multiple flowers, bees facilitate the pollination process, enabling the plants to reproduce. Both species gain advantages from this relationship, illustrating the fundamental principle of mutualism.

On the other hand, other options do not describe mutualism accurately. One species benefiting at the other's expense contradicts the essence of mutualism, as it describes parasitism or predation rather than a cooperative interaction. The idea that both species provide food for each other can be true in some mutualistic relationships, but it does not capture the broad notion of mutual benefit that defines all mutualistic interactions. Lastly, the notion that none of the species involved benefit clearly does not align with mutualism, as this would describe a neutral or negative interaction. Thus, the defining characteristic of mutualism is that both species