The correct answer is C. Genetic analysis
Step-by-step explanation:
In biology, two organisms have a phylogenetic relationship if they share a common ancestor and therefore have genetic similarities although in most cases there are also similarities in morphology, physiology, etc. However, two organisms might have similarities in morphology and physiology without genetic similarities. Due to this, if you need to determine whether two species are related or not the best method is a genetic analysis as only those organisms that share a common ancestor (phylogenetic relationship) are genetically similar.