Consider Four Species of Conifers

Consider four species of conifers.Species A and B are sister species.Species C and D are also sister species.The clade containing species A and B is a sister to the clade containing species C and D.Not counting the root as a node, how many nodes would be found in a phylogenetic tree of species A, B, C, and D?

A) One
B) Two
C) Three
D) Four
E) Five