Which polynomial correctly combines the like terms and expresses the given polynomial in standard form?

8mn5 – 2m6 + 5m2n4 – m3n3 + n6 – 4m6 + 9m2n4 – mn5 – 4m3n3
n6 + 7mn5 + 14m2n4 – 5m3n3 – 6m6
–2m6 – 5m3n3 + 14m2n4 + 7mn5 + n6
14m2n4 + 7mn5 – 6m6 – 5m3n3 + n6
n6 – 6m6 + 7mn5 + 14m2n4 – 5m3n3

First option is incorrect since 5m2n4 and 9m2n4 can still be added together, and also 4m3n3 and – m3n3, and lastly, 8mn5 and – mn5.

Second option is correct with the standard form from highest exponent then another variable decreasing in exponent: n6 + 7mn5 + 14m2n4 – 5m3n3 – 6m6.

Others are incorrect such that terms haven't been simplified enough and that the two highest exponents n6 and m6 are not beside each other or should not follow each other.

Among the given polynomials above, only the first polynomial is not correctly combined as there are still like terms that are not expressed as a single term. These are the terms with variables: mn5, m6, m2n4, and m3n3.

Additionally, among the choices only third polynomial is arranged in standard form with decreasing exponents based on the variable m. Therefore, the answer is the third polynomial. 

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