Final answer:
The true statement concerning the evolution of mutualisms and commensalisms is that all the mentioned possibilities are true: host-parasite relationships can evolve into commensalisms or mutualisms, and parasites and hosts often coevolve.
Step-by-step explanation:
The correct statement about the evolution of mutualisms and commensalisms is: 4) All of the above are true.
Mutualism is a symbiotic relationship where both species benefit. For example, bees gather nectar from flowers and in the process, they pollinate the plants, which is crucial for plant reproduction. Commensalism involves one species benefitting while the other is not affected significantly, like birds that live in trees but do not harm or benefit the trees.
Parasitism is where the parasite benefits and the host is harmed. Over time, these relationships can evolve; host-parasite relationships may become less harmful and transform into commensalism or even mutualism. An example of this evolution could be gut microbiota, which likely started out as parasites but have evolved to be essential for digestion in humans. Co-evolution between parasites and hosts often occurs as each adapts to the changes in the other.