( ( the ( lowest frequencies ) ) ( ( are ( radio waves ) ) . ) )
(ROOT (S (NP (DT the) (JJS lowest) (NNS frequencies)) (VP (VBP are) (NP (NN radio) (NNS waves))) (. .)))
the lowest frequencies are radio waves.
(ROOT (S (NP (NNP Am) (NN radio) (NNS waves)) (VP (VBP exist) (PRT (RP in)) (NP (DT the) (ADJP (QP (CD 540) (TO to) (CD 1600))) (NN khz) (NN frequency) (NN range))) (. .)))