( ( ( D. ( 2.3 Explain ) ) ( ( the ( Darwin-Wallace theory ) ) ( of ( evolution ( by ( natural selection ) ) ) ) ) ) . )
(ROOT (NP (NP (NNP D.) (NNP 2.3) (NNP Explain)) (NP (NP (DT the) (JJ Darwin-Wallace) (NN theory)) (PP (IN of) (NP (NP (NN evolution)) (PP (IN by) (NP (JJ natural) (NN selection)))))) (. .)))
D.2.3 Explain the Darwin-Wallace theory of evolution by natural selection.
(ROOT (S (NP (NP (NNP Theevolution)) (PP (IN by) (NP (JJ natural) (NN selection) (NN theory)))) (VP (VBZ explains) (SBAR (WHADVP (WRB how)) (S (NP (NP (NNS populations)) (PP (IN of) (NP (NNS organisms)))) (VP (MD can) (VP (VB change) (PP (IN over) (NP (NN time)))))))) (. .)))