( ( Explain ( how ( ( natural selection ) ( is ( ( the basis ) ( of ( ( the theory ) ( of evolution ) ) ) ) ) ) ) ) . )
(ROOT (S (VP (VB Explain) (SBAR (WHADVP (WRB how)) (S (NP (JJ natural) (NN selection)) (VP (VBZ is) (NP (NP (DT the) (NN basis)) (PP (IN of) (NP (NP (DT the) (NN theory)) (PP (IN of) (NP (NN evolution)))))))))) (. .)))
Explain how natural selection is the basis of the theory of evolution.
(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)))))))) (. .)))