Which polynomial is prime?

A factors by grouping as (x + 3)(x² − 2), B as (x − 2)(x² + 3), and C as 2(x + 1)(2x³ − 1), so none is prime. For D, the possible rational roots (±1, ±2, ±1/2) do not make the polynomial zero, and matching coefficients shows it has no factorization into two quadratics with rational coefficients. Thus 2x⁴ + x³ − x + 2 is prime.

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