Final answer:
The Markov model helps predict the make-up of a community when the species pool is known, which is useful in ecology for modeling how communities evolve over time given the reproductive and nutritional strategies of organisms.
Step-by-step explanation:
Among the statements provided about the Markov model, the one that is true is that the model helps to predict the make-up of a community when the species pool is known (Option a). A Markov model is a stochastic model that is used to predict the state of a system over time where the future state depends only on the current state and not on the sequence of events that preceded it. This principle can be particularly useful in ecology for modeling how communities change over time, assuming all the different species that could potentially inhabit the community are known. This aligns with the broader concept in ecology that organisms have reproductive strategies that, along with their nutritional strategies and habitat types, can influence their success and persistence in a given community, thus shaping community structure through a sequence of changes as the community matures.