Answer: d. only similarities that have evolved since the time of their common ancestor.
Explanation:
A taxon is a group of one or more members of the organisms that forms a single unit based upon common characteristics they acquire through inheritance or they acquire from their environment.
The taxon can include the shared characteristics that suggests that all living beings are descendants of the common ancestor. They exhibit similarities in the genetic make up that is DNA. It is expressed by the genes through transcription and translation.