Plants that grow in deserts of different continents have some traits in common, such as those mentioned in the second, and the third answer options: B. they share special adaptations that are analogous, and C. they show more similarities to other plants on the same continent that they do to each other. This is because different and non-closely related species can develop similar traits to exploit a particular resource, in this case, it would be the space and nutrients availability present in this kind of ecosystem (deserts), and, since they evolve in the same continent, and in hence, evolved from ancient plants living there, they would be more related to them, than to the other plants from other places.