Final answer:
A phylogenetic tree represents the genetic relationships among species by showing how contemporary species are related to common ancestors, not necessarily in regular time intervals or including only extinct species, nor displaying geographic distribution.
Step-by-step explanation:
The question regards the correct interpretation of a phylogenetic tree, which is a diagram used to depict the evolutionary relationships among various species. When we look at the given statements, the true aspect of a phylogenetic tree is that it represents genetic relationships among species. Specifically, the trees map out the ancestral lineages and how current species have diverged from common ancestors over time. The length of each branch on the phylogenetic tree is proportional to the amount of time since the most recent common ancestor, indicating the relative times in the past that the species shared common ancestors. Therefore, this allows us to infer evolutionary patterns and relationships, although the specific duration of time represented by each branch may not be indicated unless specifically marked on the diagram.
As such, the correct option in this case would be (b) It represents genetic relationships among species. While option (d) discusses temporal aspects that may be represented in some phylogenetic trees, it is not true that phylogenetic trees only include extinct species. Additionally, option (a) is not entirely accurate because branches do not necessarily represent regular time intervals, and option (c) is incorrect as phylogenetic trees do not display geographic distribution of species.