( This ( ( is ( because ( ( resonant frequency ) ( is ( ( correlated ( with tension ) ) ( as ( in ( a ( taunt string ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT This)) (VP (VBZ is) (SBAR (IN because) (S (NP (JJ resonant) (NN frequency)) (VP (VBZ is) (VP (VBN correlated) (PP (IN with) (NP (NN tension))) (PP (IN as) (PP (IN in) (NP (DT a) (JJ taunt) (NN string))))))))) (. .)))
This is because resonant frequency is correlated with tension as in a taunt string.
(ROOT (S (NP (JJ Stringed) (NNS instruments)) (VP (MD can) (VP (VB help) (VP (VB show) (NP (NP (DT the) (NN relationship)) (PP (IN between) (NP (NN tension) (CC and) (NNS frequencies)))) (PP (IN in) (NP (NNS strings)))))) (. .)))