Which polynomial is prime?

Combine like terms in choice D to get 3x² − 5x + 3. Its discriminant is (−5)² − 4(3)(3) = 25 − 36 = −11, so it has no rational roots and cannot be factored into linear polynomials with integer coefficients. The other choices factor, so choice D, 3x² − 5x + 3, is prime.

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