( ( c -RRB- ) ( mutagens ( ( are ( ( chemicals , ) ( ( ionizing radiation ) ( that ( can ( cause mutations ) ) ) ) ) ) . ) ) )
(ROOT (S (LST (LS c) (-RRB- -RRB-)) (NP (NNS mutagens)) (VP (VBP are) (NP (NP (NNS chemicals)) (, ,) (NP (NP (VBG ionizing) (NN radiation)) (SBAR (WHNP (WDT that)) (S (VP (MD can) (VP (VB cause) (NP (NNS mutations))))))))) (. .)))
c) mutagens are chemicals, ionizing radiation that can cause mutations.
(ROOT (S (NP (NNP Cancer)) (VP (VBZ is) (VP (VBN caused) (PP (IN by) (NP (NP (NNS mutations)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (MD can) (VP (VB be) (VP (VBN caused) (PP (IN by) (NP (NNS pathogens) (, ,) (NNS chemicals) (, ,) (CC or) (NN radiation)))))))))))) (. .)))