( ( ( Ultraviolet radiation ) ( from ( sun exposure ) ) ) ( ( is ( ( the ( primary cause ) ) ( of ( skin cancer ) ) ) ) . ) )
(ROOT (S (NP (NP (JJ Ultraviolet) (NN radiation)) (PP (IN from) (NP (NN sun) (NN exposure)))) (VP (VBZ is) (NP (NP (DT the) (JJ primary) (NN cause)) (PP (IN of) (NP (NN skin) (NN cancer))))) (. .)))
Ultraviolet radiation from sun exposure is the primary cause of skin cancer.
(ROOT (S (NP (NP (NNP Exposure)) (PP (TO to) (NP (JJ ultraviolet) (NN radiation)))) (VP (MD can) (VP (VP (VB increase) (NP (NP (DT the) (NN amount)) (PP (IN of) (NP (NN pigment)))) (PP (IN in) (NP (DT the) (NN skin)))) (CC and) (VP (VB make) (S (NP (PRP it)) (VP (VB appear) (NP (JJR darker))))))) (. .)))