Find the 5th term of the expansion of (x + y)9.

For the expansion of (x + y)^9, the 5th term uses the binomial coefficient \(\binom{9}{4}\), with powers \(x^{9-4}y^4\). Since \(\binom{9}{4}=126\), the term is \(126x^5y^4\), which is choice D.

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