# Not as complex as it looks

For any positive integer $$n$$, we define the cyclotomic polynomial $$\Phi_n(x)=\prod(x-w)$$, where the product is taken over all primitive $$n$$th roots of unity, $$w$$.

Which of the statements (a), (b), (c), (d), (e), in this order, is the FIRST to be true?

All coefficients of all cyclotomic polynomials are

(a) 0, 1, or -1

(b) integers

(c) rational

(d) real

(e) complex

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