Which expression is not a polynomial in (n)?

Correct answer: (n^{4/3}+2)

The direct answer is C: \\(n^{4/3}+2\\) is not a polynomial in n. To test an expression, inspect every exponent of the variable. In a polynomial, each exponent must be a whole number that is zero or positive. Option A has powers 4, 2, and 0, so it is a polynomial. Option B has powers 1 and 0, so it is also a polynomial. Option C contains \\(n^{4/3}\\); the exponent \\(4/3\\) is fractional, not an integer, so it does not meet the definition. Option D contains \\(n^0\\), and exponent 0 is allowed; indeed \\(n^0=1\\) for nonzero n, so this becomes a constant expression. Thus C is correct. Option A is wrong as an answer because all its powers are permitted. Option B is wrong for the same reason. Option D is wrong because zero is specifically an allowed exponent, not a forbidden one. Do not confuse a large exponent with an invalid exponent: 4 is valid, while a fractional exponent such as \\(4/3\\) is not valid in a school-level polynomial. Exam cue: a variable may appear only with powers 0, 1, 2, 3, etc.