the good , which is its essential problem 
(ROOT (NP (NP (DT the) (NN good)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBZ is) (NP (PRP$ its) (JJ essential) (NN problem)))))))
(ROOT (NP (NP (DT ) (NN )) (, ) (SBAR (WHNP (WDT )) (S (VP (VBZ ) (NP (PRP$ ) (JJ ) (NN )))))))