To investigate the evolutionary relationships among four species of ground beetles ($P$, $Q$, $R$, and $S$), scientists compared the amino acid sequences of a highly conserved 100-amino-acid region of cytochrome c. The table below shows the number of amino acid differences between each pair of species.

$$\begin{array}{ccccc}Species& P& Q& R& S\\ P& 0& 3& 12& 19\\ Q& 3& 0& 11& 18\\ R& 12& 11& 0& 15\\ S& 19& 18& 15& 0\end{array}$$

Based on this molecular phylogeny data, which of the phylogenetic trees (A, B, C, or D) correctly represents the evolutionary relationships among these four species?