( ( The ( planetary scientists ) ) ( ( say ( that ( ( ( the ( ( most likely ) explanation ) ) ( for this ) ) ( would ( ( ( be ( ( an ocean ) ( of ( ( salt water ) ( ( several kilometers ) deep ) ) ) ) ) , ) ( with ( ( a ( salt content ) ) ( comparable ( to ( that ( of ( ( Earth 's ) oceans ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (JJ planetary) (NNS scientists)) (VP (VBP say) (SBAR (IN that) (S (NP (NP (DT the) (ADJP (RBS most) (JJ likely)) (NN explanation)) (PP (IN for) (NP (DT this)))) (VP (MD would) (VP (VB be) (NP (NP (DT an) (NN ocean)) (PP (IN of) (NP (NP (NN salt) (NN water)) (ADVP (NP (JJ several) (NNS kilometers)) (RB deep))))) (, ,) (PP (IN with) (NP (NP (DT a) (NN salt) (NN content)) (ADJP (JJ comparable) (PP (TO to) (NP (NP (DT that)) (PP (IN of) (NP (NP (NNP Earth) (POS 's)) (NNS oceans))))))))))))) (. .)))
The planetary scientists say that the most likely explanation for this would be an ocean of salt water several kilometers deep, with a salt content comparable to that of Earth's oceans.
(ROOT (S (NP (NP (JJS Most)) (PP (IN of) (NP (NP (NN earth) (POS 's)) (NN water)))) (VP (VBZ is) (VP (VBN located) (PP (IN in) (NP (NNS oceans)))))))