( ( ( iv , ) ( clouds ( of hydrogen ) ) ) ( gravitationally ( ( collapse ( It ( ( is ( through fusion ) ) ( that ( ( ( most ( the elements ) ) ( that ( ( make up ) ( biological systems ) ) ) ) ( were created ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (NP (NN iv)) (, ,) (NP (NP (NNS clouds)) (PP (IN of) (NP (NN hydrogen))))) (ADVP (RB gravitationally)) (VP (VB collapse) (SBAR (S (NP (PRP It)) (VP (VBZ is) (PP (IN through) (NP (NN fusion))) (SBAR (IN that) (S (NP (NP (RB most) (DT the) (NNS elements)) (SBAR (WHNP (WDT that)) (S (VP (VBP make) (PRT (RP up)) (NP (JJ biological) (NNS systems)))))) (VP (VBD were) (VP (VBN created))))))))) (. .)))
iv, clouds of hydrogen gravitationally collapse It is through fusion that most the elements that make up biological systems were created .
(ROOT (S (NP (DT The) (NN sun)) (ADVP (RB mostly)) (VP (VBD made) (PRT (RP up)) (PP (IN of) (NP (DT the) (NN element) (NN hydrogen)))) (. .)))