( People ( ( ( can only ) ( see ( ( the ( visible light ) ) ( which ( is ROYGBIV ) ) ) ) ) . ) )
(ROOT (S (NP (NNS People)) (VP (MD can) (ADVP (RB only)) (VP (VB see) (NP (NP (DT the) (JJ visible) (NN light)) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (ADJP (JJ ROYGBIV)))))))) (. .)))
People can only see the visible light which is ROYGBIV.
(ROOT (S (NP (PRP We)) (VP (VBP call) (NP (DT the) (JJ only) (NN light)) (SBAR (IN that) (S (NP (NNS people)) (VP (MD can) (VP (VB see) (NP (JJ visible) (NN light))))))) (. .)))