Answer: It depends on the particular phylogenetic tree in question.
Explanation: Phylogeny is used to determine relationship between items e.g. species, population, organisms, etc. A phylogenetic tree is a graphical illustration of phylogenetic relationship.
Consider the attached phylogenetic tree, organism C and E share the same common ancestor because they clustered at the same node/distance. This can also be referred to as a CLADE.
B and D also share common ancestor for the same reason and can also be referred to as a CLADE.
